This application claims priority from Korean Patent Application Nos. 10-2007-00116901 and 10-2007-0138983, respectively, filed on Nov. 15, 2007 and Dec. 27, 2007, the disclosures of which are incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a power transmitting apparatus, and more particularly, to an apparatus and a system for transmitting and receiving power wirelessly.
2. Description of the Related Art
Recently, wireless power transmission technology that can wirelessly provide power to a variety of mobile devices or industrial robots has become an issue. Inductive coupling and radiative coupling are typically used for wireless power transmission.
In inductive coupling, a number of coils are used such that a magnetic field is strongly induced in one direction, and when coils which resonate at a similar frequency become very close to each other, coupling takes place, and power transfer thereby occurs between the coils. However, the inductive coupling enables power transfer within a very limited range, and power transfer is not possible if the coils are not accurately aligned with each other.
In contrast, in radiative coupling, antennas such as a monopole or a planar inverted F antenna (PIFA) are used to radiate power while time varying electric fields and magnetic fields interact with each other. If two antennas have the same frequency, power can be transferred between the antennas according to the polarization properties of an incident wave. However, in this case, power is radiated in all directions, and thus efficient power transmission is hard to be achieved.
The present invention provides a wireless power transmitting apparatus and a wireless power transmitting and receiving system which over a short distance range have higher power transmission efficiency than the power transmission efficiency of a radiative coupling method and can transmit power over a longer distance than in an inductive coupling method.
Additional aspects of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.
The present invention discloses an apparatus for transmitting power wirelessly, the apparatus comprising: a dielectric resonator which generates evanescent waves in a predetermined direction in order to transmit power; and a loop antenna which is coupled to a surface of the dielectric resonator and supplies power to the dielectric resonator.
The dielectric resonator may generate evanescent waves in directions perpendicular to top and bottom surfaces of the dielectric resonator in order to transmit power. The dielectric resonator may perform power transmission by radiation in directions parallel to the top and bottom surfaces of the dielectric resonator. The dielectric resonator may transmit relatively more power to a power receiving apparatus using evanescent waves than radiation when the dielectric resonator is within a predetermined range of distance from the power receiving apparatus and may transmit relatively more power by radiation than by evanescent waves when a distance of the dielectric resonator from the power receiving apparatus exceeds the predetermined range.
The present invention also discloses an apparatus for receiving power wirelessly, the apparatus comprising: a dielectric resonator which receives evanescent waves generated in a predetermined direction using a dielectric in order to receive power; and a loop antenna which is coupled to a surface of the dielectric resonator and receives power from the dielectric resonator.
The present invention also discloses a system for transmitting and receiving power wirelessly, the system comprising: a power transmitting apparatus which includes a dielectric resonator and a loop antenna and transmits power provided from the loop antenna to a power receiving apparatus using evanescent waves generated by the dielectric resonator; and the power receiving apparatus which includes a dielectric resonator that receives the power using the evanescent waves generated by the power transmitting apparatus and a loop antenna that transmits the received power to an external device, wherein each of the power transmitting apparatus and the power receiving apparatus is formed by the dielectric resonator and the loop antenna which are coupled to each other.
The power transmitting and receiving efficiency may increase as resonant frequencies of each dielectric resonator of the power transmitting apparatus and the power receiving apparatus become closer to each other.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention, and together with the description serve to explain the aspects of the invention.
The invention is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. Hereinafter, in describing the present invention, detailed descriptions of relevant functions or structures well-known to those skilled in the art will be omitted when it is considered that the descriptions obscure the point of the present invention. The terms used herein are defined in consideration of the functions of elements in the present invention, and may be varied according to the intentions or the customs of a user and an operator.
A short-distance wireless power transmitting apparatus employed by the present invention is a dielectric resonator antenna.
Referring to
Due to the structural characteristic of the dielectric resonator having a high dielectric constant, resonance occurs in the dielectric resonator 10 and a cutoff mode is generated outside of the dielectric resonator 10 so that an evanescent wave is formed. The radiation spreads in all directions from the side of the dielectric resonator 10. By using these characteristics of the dielectric resonator 10, power is transmitted using evanescent waves, which are formed in directions perpendicular to the top and bottom surfaces of the dielectric resonator 10, or is transmitted in a direction parallel to the top and bottom surfaces of the dielectric resonator 10 through radiation.
The dielectric resonator may transmit relatively more power to a power receiving apparatus within a predetermined range of distance using evanescent waves and may transmit relatively more power by radiation when a distance from the power receiving apparatus exceeds the predetermined distance range.
The structure of the dielectric resonator 10, which forms the wireless power transmitting apparatus according to the present embodiment of the present invention, will now be described in detail.
The dielectric resonator 10 forms a TE016 mode, and a magnetic field (H field) is formed in a direction z. The direction of the H field is the same as a direction of a magnetic field in a power supply structure employing the loop antenna 20, which will be described later, thereby enabling the power supply using the loop antenna 20. When resonance occurs in the dielectric resonator 10, a cutoff mode is formed in the direction z so that evanescent waves are created and the radiation spreads in directions x and y.
Table 1 shows parameter values for designing a dielectric resonator which operates at a frequency of 835 MHz. Referring to the example dielectric resonator of
However, a design of the dielectric can be modified in various ways according to a desired frequency at which the resonator operates or characteristics of a terminal having wireless power transmission and receipt functions. Hence, the parameter values can be varied according to the intentions of a user.
The loop antenna 20 may be a micro-strip antenna which is formed by patterning a loop-shaped antenna on a substrate. The power supply structure for exciting an electromagnetic field is formed in a loop shape, and a micro-strip structure is employed to improve the precision of fabrication and facilitate coupling between the loop antenna 20 and the dielectric resonator 10. However, the present invention is not limited to the loop antenna described above, and various modified forms of antenna can be used, for example, using a loop-shaped antenna as it is.
Table 2 shows design parameters of the power supply structure using the loop antenna 20. In the example shown in
However, a shape of the loop antenna 20 can be varied according to a desired frequency or a terminal having wireless power transmission or receipt function. Therefore, the parameter values shown in Table 2 can be changed according to the intentions of a user.
The loop antenna 20 has a magnetic field “H field” formed perpendicular to a loop plane, and a resonant frequency may be in an UHF, HF, or LF band according to a desired frequency, or characteristics of a terminal having a wireless power transmission or receipt function. As described above, the dielectric resonator 10 has a magnetic field formed in a direction z in a TE016 mode, and the direction of the magnetic field of the dielectric resonator 10 is the same as that of the magnetic field of the power supply structure, thereby enabling the power supply using the loop antenna 20.
As shown in
Also, as shown in
According to the current embodiment of the present invention, since a variety of forms can be employed for the dielectric resonator, it is possible to design a product that is most efficient. In other words, the shape and size of the dielectric resonator, which can be varied according to a desired dynamic frequency, allow easy application of the dielectric resonator to various products. Furthermore, various modifications of the dielectric resonator are possible to control the ratio of evanescent waves to radiation in a manner that helps obtain the most power transmission efficiency within a desired power transmission distance range.
Additionally, the shape of the dielectric resonator can be varied according to a desired frequency or characteristics of a terminal having a wireless power transmission or receipt function. Hence, the design of the dielectric resonator can be changed according to the intentions of a user.
A wireless power receiving apparatus according to an embodiment of the present invention is configured using the same structure as that of the wireless power transmitting apparatus described above. That is, the wireless power receiving apparatus comprises a dielectric resonator that receives power by receiving evanescent waves generated in a particular direction using a dielectric, and a loop antenna that is coupled to one surface of the dielectric resonator and receives power from the dielectric resonator. Since the structures of the dielectric resonator and the loop antenna have been already described above, a description of the structure of the wireless power receiving apparatus will be omitted.
The power transmitting apparatus 1 transmits power from a power source through a loop antenna to the power receiving apparatus 2 or 3 using evanescent waves that are created by the dielectric resonator. The power transmitting apparatus 1 includes the dielectric resonator and the loop antenna which is coupled to a surface of the dielectric resonator.
The power receiving apparatus 2 or 3 receives power through the dielectric resonator using the evanescent waves generated by the power transmitting apparatus 1, and transmits the received power to a desired device through a loop antenna. The power receiving apparatus 2 includes a dielectric resonator and the loop antenna which is coupled to a surface of the dielectric resonator.
A structure for coupling the power transmitting apparatus 1 and the power receiving apparatus 2 or 3 is shown in
In a perpendicular arrangement, radiation does not occur in a direction z, and thus transmission through evanescent waves is possible. In a parallel arrangement, radiation occurs directly between distance apparatuses, and it is thereby possible to transmit the power to a distance apparatus through radiation or to transmit power to a close apparatus through radiation and evanescent waves.
In
In the case of the power receiving apparatus 3 which is placed parallel to the top or bottom surface of the dielectric resonator of the power transmitting apparatus 1, it is more efficient to transmit power by radiation in a direction parallel to the top and bottom surface of the dielectric resonator of the power transmitting apparatus 1.
If the power receiving apparatus is placed at an angle between 0 and 90 degrees with respect to the dielectric resonator of the power transmission apparatus 1, evanescent waves may be used mostly to transmit and receive power between power transmitting and receiving apparatuses which are placed within a predetermined distance, and radiation may be used mostly to transmit and receive power between power transmitting and receiving apparatuses that are placed further apart than the predetermined distance. Moreover, the power transmitting and receiving efficiency of the power transmission apparatus 1 and the power receiving apparatus 2 or 3 increase as the resonant frequencies of each of the dielectric resonators become more similar to each other.
As described above, according to the present invention, a wireless power transmission apparatus efficiently transmits power using evanescent waves of a dielectric resonator.
Additionally, the dielectric resonator produces evanescent waves in a perpendicular direction and radiation in a horizontal direction, thereby enabling efficient power transmission according to a distance between the wireless power transmitting apparatus and the wireless power receiving apparatus. When the wireless power transmitting and receiving apparatuses are close to each other, strong coupling through the evanescent waves is achieved in a perpendicular direction, and as the wireless power transmitting and receiving apparatuses become further from each other, coupling by radiation becomes stronger in a horizontal direction. That is, in a short distance range, power transmission by the evanescent waves is more efficient than power transmission by radiation, and in a long distance range, power transmission occurs by evanescent waves along with radiation. Therefore, wireless power transmission can be efficiently performed in both long and short distance ranges.
Power transmission is performed using evanescent waves when the dielectric resonator is in a perpendicular position, and power transmission is performed by radiation when the dielectric resonator is in a horizontal position.
Furthermore, the resonator can have various shapes besides a cylinder shape, and thus the range of application of the dielectric resonator can be widened.
While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The preferred embodiments should be considered in descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.
Number | Date | Country | Kind |
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10-2007-0116901 | Nov 2007 | KR | national |
10-2007-0138983 | Dec 2007 | KR | national |
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