JP2012178479A - Wireless power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless power transmission system in which expansion of a transmitting-side electronic apparatus in scale is suppressed, further, variance in power transmission according to a location of a receiving-side electronic apparatus is reduced and moreover, the receiving-side electronic apparatus is further small-sized.SOLUTION: A wireless power transmission system 1 comprises a transmitting-side electronic apparatus 2 including a transmitting-side resonator 21 having a transmitting-side spiral coil 21a and a receiving-side electronic apparatus 3 including a receiving-side resonator 31 having a receiving-side spiral coil 31a of which the spiral diameter is smaller than that of the transmitting-side spiral coil 21a. In the transmitting-side spiral coil 21a, the presence/absence of an electric lead wire 21aa and an inter-wire pitch (g) are different between a peripheral area N and an inner area M and around the receiving-side spiral coil 31a, an electric lead wire 31aa is wound more tightly than the transmitting-side spiral coil 21a. The transmitting-side resonator 21 and the receiving-side resonator 31 are resonated in a predetermined resonant frequency, thereby wirelessly transmitting power from the transmitting-side electronic apparatus 2 to the receiving-side electronic apparatus 3.

Description

  The present invention relates to a resonance type wireless power transmission system.

  Conventionally, research and development of a wireless power transmission system that wirelessly (contactlessly) transmits power from a transmission-side electronic device to a reception-side electronic device has been actively conducted. Since the wireless power transmission system does not require mechanical contact, it has advantages such as high durability and low noise. Such wireless power transmission systems include those that use electromagnetic waves that propagate far and those that use coupling by an electromagnetic field (evanescent field) that does not propagate far and exists only in the vicinity. In the latter case, if the receiving side electronic device that receives power is present, the power (energy) of the transmitting side electronic device is received on the receiving side according to the coupling with the transmitting side electronic device. An electromagnetic induction method and a resonance method are mainly proposed.

  A resonance-type wireless power transmission system is configured such that the resonance frequency of the transmission-side resonator provided in the transmission-side electronic device matches the resonance frequency of the reception-side resonator provided in the reception-side electronic device, thereby resonating. The power is transmitted by causing the receiving side resonator to resonate with the electromagnetic field from the resonator. In general, this method can increase the transmission efficiency compared with the electromagnetic induction method, and can prevent the surrounding objects that do not resonate from being affected. As a resonance-type wireless power transmission system, for example, Patent Document 1 describes a helical coil and a capacitor coupled in parallel as a transmission-side resonator and a reception-side resonator. In Patent Document 1, the structures and sizes of the transmission-side resonator and the reception-side resonator are made the same so that their resonance frequencies are matched.

  Patent Document 2 describes a helical coil having a large diameter as a transmitting side resonator and a spiral coil having a small diameter as a receiving side resonator. In Patent Document 2, the structures and sizes of the transmission-side resonator and the reception-side resonator are made different, and the resonance frequencies thereof are matched. In Patent Document 2, the reception-side electronic device such as a portable communication terminal or a computer is miniaturized by using a reception-side resonator as a spiral coil and relatively reducing the volume occupied by the reception-side resonator.

US Patent Publication No. 2009/0015075 JP 2010-279239 A

  By the way, when considering a wireless power transmission system including a transmission-side electronic device that is fixedly installed and a reception-side electronic device that is carried and moved, it is desired that the reception-side electronic device be as small as possible. In addition, the transmission-side electronic device increases, for example, an area for transmitting power or reduces variations in power transmission depending on the location so that sufficient power is transmitted to the reception-side electronic device in the widest possible range. Is preferred.

  However, if the transmission-side resonator is configured using the helical coil described in Patent Documents 1 and 2 in order to increase the area for transmitting power, the transmission-side resonator becomes thick and the entire transmission-side electronic device is Invite larger size. In addition, regarding the reception-side electronic device, if the reception-side resonator is configured using the helical coil described in Patent Document 1, the reception-side electronic device is also increased in size, so that the reception-side electronic device is small enough to be portable. difficult. Further, if the spiral coil described in Patent Document 2 is used, it is considered that the receiving-side electronic device can be considerably reduced in size, but the need for further downsizing is considered high.

  The present invention has been made in view of the above reasons, and its purpose is to suppress the enlargement of the entire apparatus even when the area for transmitting power is increased for the transmission-side electronic apparatus, and the reception-side electronic apparatus It is an object of the present invention to provide a wireless power transmission system that is smaller in size so that there is little variation in power transmission depending on the location and the receiving-side electronic device is suitable for carrying.

  In order to achieve the above object, the wireless power transmission system according to claim 1 includes a transmission-side resonator having a transmission-side spiral coil formed by winding a conductive wire in a flat and spiral shape. A reception device including an electronic device and a reception-side resonator having a reception-side spiral coil having a spiral diameter smaller than that of the transmission-side spiral coil, which is formed by spirally winding an electric conductor in a planar shape. The transmission-side spiral coil includes a peripheral region and an inner region located inside the peripheral region and including the center of the spiral, and the presence or absence of the electric conductor or the pitch between the lines is The receiving side spiral coil is wound more densely around the electrical conductor than the transmitting side spiral coil, and the transmitting side resonator resonates at a predetermined resonance frequency. By the receiving side resonator resonates at a resonance frequency of the transmitting-side resonator, and wherein the transmitting power wirelessly to the receiving electronic apparatus from the transmitting-side electronic device.

  A wireless power transmission system according to a second aspect is the wireless power transmission system according to the first aspect, wherein the transmission-side spiral coil is provided with the electrical conductor only in the peripheral region.

  The wireless power transmission system according to claim 3 is the wireless power transmission system according to claim 2, wherein the transmission-side spiral coil has a radial length of the peripheral region that is larger than a radius of the inner region. It is characterized by being smaller.

  A wireless power transmission system according to a fourth aspect is the wireless power transmission system according to the third aspect, wherein the transmission-side spiral coil has a radial length of the peripheral region that is 6 times a radius of the inner region. It is characterized by being less than 1 / minute.

  The wireless power transmission system according to claim 5 is the wireless power transmission system according to claim 1, wherein the transmission-side spiral coil is continuously provided in the peripheral region and the inward region, In the region, the electric conductor is densely wound, and in the inner region, the electric conductor is sparsely wound.

  The wireless power transmission system according to claim 6 is the wireless power transmission system according to claim 5, wherein the transmission-side spiral coil has a radial length of the peripheral region that is 9 times a radius of the inner region. It is characterized by being less than 1 / minute.

  The wireless power transmission system according to claim 7 is the wireless power transmission system according to any one of claims 1 to 6, wherein the transmission-side spiral coil is open at both ends that resonates at ½ wavelength. It is characterized by being.

  The wireless power transmission system according to claim 8 is the wireless power transmission system according to any one of claims 1 to 7, wherein the reception-side resonator has a line pitch between electric conductors of the reception-side spiral coil. Is less than or equal to one-half of the pitch between the electrical conductors of the transmitting spiral coil.

  The wireless power transmission system according to claim 9 is the wireless power transmission system according to any one of claims 1 to 8, wherein the reception-side resonator includes a capacitor between both ends of the reception-side spiral coil. It is characterized by being.

  The wireless power transmission system according to claim 10 is the wireless power transmission system according to claim 9, wherein the reception-side spiral coil has a diameter equal to or less than 1/7 of the diameter of the transmission-side spiral coil. It is characterized by being.

  According to the present invention, in a wireless power transmission system, a spiral coil is used for a transmission-side resonator of a transmission-side electronic device and a reception-side resonator of a reception-side electronic device, and a peripheral region and an inner region of the transmission-side spiral coil are used. Because the electrical conductor of the receiving side spiral coil is wound more densely than the transmitting side spiral coil, the area for transmitting power is increased for the transmitting side electronic device. Even when the size of the entire device is suppressed, variation in power transmission due to the location of the receiving-side electronic device is reduced, and the receiving-side electronic device can be further miniaturized to be suitable for carrying. Become.

It is a schematic diagram which shows the structure of the wireless power transmission system which concerns on embodiment of this invention. It is a top view which shows the example of the transmission side spiral coil of a wireless power transmission system same as the above. It is a top view which shows another example of the transmission side spiral coil of a wireless power transmission system same as the above. It is a top view which shows another example of the transmission side spiral coil as a reference. The example of the receiving side resonator of a wireless power transmission system same as the above is shown, Comprising: (a) is a top view, (b) is an enlarged plan view. It is a schematic diagram which shows the experimental structure for a wireless power transmission system same as the above. It is a figure which shows the transmission characteristic of the electric power of a wireless power transmission system same as the above.

  Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings. As schematically shown in FIG. 1, a wireless power transmission system 1 according to an embodiment of the present invention includes a transmission-side electronic device 2 and a reception-side electronic device 3, and uses an electromagnetic field (evanescent field) without using electromagnetic waves. ) Is used to wirelessly transmit power from the transmission side electronic device 2 to the reception side electronic device 3. The wireless power transmission system 1 is suitable for a system in which the transmission-side electronic device 2 is fixedly installed by embedding in a floor or a wall, and the reception-side electronic device 3 can carry power while being carried around. Applied to.

  As shown in FIG. 1, the transmission-side electronic device 2 includes a transmission-side resonator 21 that resonates at a predetermined frequency. The transmission-side resonator 21 has an electric conductor 21aa planarly wound in a spiral shape. A transmission-side spiral coil 21a is formed.

  The transmission-side spiral coil 21a is as shown in FIGS. 2 and 3, and as shown in FIG. 4, all the line pitches g of the electric conducting wires 21aa are constant from the center of the spiral to the outermost side of the spiral. It is not a so-called uniform winding spiral coil that is kept and wound. That is, the transmission-side spiral coil 21a includes the peripheral region N (the region between the concentric circles indicated by broken lines in FIGS. 2 and 3) and the inner region M that is located inside the peripheral region N and includes the center of the spiral. The presence / absence of the electrical conductor 21aa or the line pitch g is different.

  The transmission-side spiral coil 21a shown in FIG. 2 is divided into two regions, a peripheral region N and an inner region M located inside the peripheral region N, and the electric power from the inner end of the spiral to the outer end of the spiral. The conducting wire 21aa is provided only in the peripheral region N, that is, an edge-wise spiral coil (edge-wise spiral coil). The electric conducting wire 21aa is densely wound (with a short line pitch g). More specifically, the transmission-side spiral coil 21a of the edgewise winding generally has a radial length (a radial length from the innermost side to the outermost side of the electric conducting wire 21aa) n of the peripheral region N in the inner region. It is smaller than the radius of M (the length in the radial direction from the center of the spiral to the innermost side of the electric conductor 21aa) m. The transmission-side spiral coil 21a shown in FIG. 2 has a length n of 1/6 or less of the length m.

  The transmission-side spiral coil 21a shown in FIG. 3 is divided into two regions, a peripheral region N and an inner region M, and is continuously provided from the peripheral region N to the inner region M. In the peripheral region N, The electric conducting wire 21aa is densely wound, and in the inner region M, the electric conducting wire 21aa is sparsely wound (with a larger inter-line pitch g than the peripheral region N), ie, edgewise winding + equal It is a spiral coil of winding. In the transmission-side spiral coil 21a shown in FIG. 3, the length n in the radial direction of the peripheral region N is equal to or less than 1/9 of the length m in the radial direction of the inner region M.

  The transmission side spiral coil 21a is not limited in its resonance method, that is, the resonance wavelength and the processing at both ends, but those having both ends open as shown in FIGS. For example, it is advantageous in increasing the area for transmitting power, and is preferable from the viewpoint of ease of installation and low energy loss.

  In order to send a transmission signal of power to the transmission-side resonator 21 and cause it to resonate, as shown in FIG. 1, a transmission-side coupling loop 22 coupled to the transmission-side spiral coil 21a with an electromagnetic field is used. it can. A transmission signal with high frequency power from the transmission signal generation circuit 23 is input to the transmission side coupling loop 22. The transmission signal of power input to the transmission side coupling loop 22 is sent to the transmission side resonator 21 with the impedance matched.

  Next, the receiving-side electronic device 3 will be described. The reception-side electronic device 3 includes a reception-side resonator 31 that resonates at the same resonance frequency as that of the transmission-side resonator 21, and the reception-side resonator 31 has an electrical conductor 31 aa similar to the transmission-side resonator 21. The receiving-side spiral coil 31a is formed to be planar and wound in a spiral shape. The reception-side spiral coil 31a has a smaller spiral diameter than the transmission-side spiral coil 21a.

  In order to reduce the diameter of the reception side spiral coil 31a, as shown in FIG. 5, the electric conducting wire 31aa is wound more densely than the electric conducting wire 21aa of the transmitting side spiral coil 21a. The inter-pitch g ′ is smaller than the inter-line pitch g of the electrical conductor 21aa (for example, half or less). The receiving resonator 31 is preferably provided with a capacitor 31b between both ends of the receiving spiral coil 31a in order to further reduce the diameter of the receiving spiral coil 31a. When the capacitor 31b is added, the resonance frequency f (Hz) of the reception-side resonator 31 follows the equation of f = 1 / (2π√ (LC)) by the inductance L of the reception-side spiral coil 31a and the capacitance C of the capacitor 31b. This is because the inductance L is small, that is, the electrical conductor 31aa of the reception-side spiral coil 31a can be short. The diameter of the reception side spiral coil 31a shown in FIG. 5 is equal to or less than one-seventh of the diameter of the transmission side spiral coil 21a by adding the capacitor 31b.

  The reception-side spiral coil 31a shown in FIG. 5 is close to edgewise winding, but the reception-side spiral coil 31a is not particularly limited in the manner of winding except for winding closely.

  In order to transmit a transmission signal of electric power from the resonating reception-side resonator 31 to the load circuit 33, as shown in FIG. 1, a reception-side coupling loop 32 that is coupled to the reception-side spiral coil 31a by an electromagnetic field is used. Can do. The power transmission signal is impedance-matched from the reception-side spiral coil 31 a via the reception-side coupling loop 32 and transmitted to the load circuit 33. The load circuit 33 is a circuit for exhibiting the function of the receiving-side electronic device 3 such as a portable communication terminal or a computer.

  In the wireless power transmission system 1 configured as described above, the transmission-side resonator 21 resonates at a predetermined frequency, and the reception-side resonator 31 resonates due to the electromagnetic field. As a result, power is wirelessly transmitted from the transmission-side resonator 21 to the reception-side resonator 31, that is, from the transmission-side electronic device 2 to the reception-side electronic device 3.

  Since the transmission-side resonator 21 uses the transmission-side spiral coil 21a in which the electric conducting wire 21aa is planarly wound in a spiral shape, the thickness does not increase even when the area for transmitting power is increased. Therefore, the enlargement of the whole apparatus can be suppressed. In addition, since the receiving-side electronic device 3 can reduce the receiving-side spiral coil 31a, the entire receiving-side electronic device 3 can be further reduced in size so as to be suitable for carrying.

  Further, since the transmission-side spiral coil 21a is formed by winding the conductive wire 21aa in a flat and spiral shape, it is possible to easily make the spiral coil other than the uniform winding. Then, as shown in FIGS. 2 and 3, the transmission-side spiral coil 21 a is configured such that the presence / absence of the electrical conductor 21 aa or the line pitch g is different between the peripheral region N and the inner region M. As shown in the experimental example, variation in power transmission depending on the location of the moving reception-side electronic device 3 can be reduced.

  Next, an experimental example of the wireless power transmission system 1 is shown. In this experimental example, a transmission side spiral coil 21a having a relatively small diameter (23.7 cm) is used so that the experiment is possible. Further, in this experimental example, the resonance frequency of both the transmitting-side resonator 21 and the receiving-side resonator 31 is set to about 25 MHz, and as shown in FIG. 6, power of about 25 MHz is transmitted to the input terminal i of the transmitting-side coupling loop 22. By inputting a signal, the receiving side spiral coil 31a (that is, the receiving side resonator 31 and the receiving side coupling loop 32) is laterally moved from the central axis A of the transmitting side spiral coil 21a (in the vertical direction of the central axis A) (see FIG. 6, the coupling coefficient (ratio of transmitted power) between the transmitting-side resonator 21 and the receiving-side resonator 31 is measured by the receiving-side coupling loop 32.

  The transmission-side spiral coil 21a of the transmission-side resonator 21 has an edgewise winding (the one shown in FIG. 2), an edgewise winding + a uniform winding (the one shown in FIG. 3), and a uniform winding (the one shown in FIG. 4). The following three types were used. For the edgewise winding, the line pitch g is 0.4 cm and the number of turns is 4.1 turns, and for the edgewise winding + uniform winding, the edgewise winding part has a line pitch g of 0.4 cm and the number of turns. Is 2.7 turns, the part of the uniform winding has a line pitch g of 2.0 cm and the number of turns is 5.3 turns, and the part of the uniform winding has a line pitch g of 1.0 cm and the number of turns is 11.4 turns. Yes.

  The receiving-side resonator 31 is the same as that shown in FIG. 5, and the receiving-side spiral coil 31a has a diameter of 3.1 cm, a line pitch g ′ of 0.2 cm, a winding number of 4.5 turns, and a capacitor 31b. The capacitance is 68 pF. The inductance of the reception side spiral coil 31a is 0.6 μH.

  FIGS. 7A, 7B, and 7C show the results obtained by measuring the distance d between the transmission side spiral coil 21a and the reception side spiral coil 31a as 2 cm, 4 cm, and 6 cm, respectively. The horizontal axis is the distance (deviation) from the central axis A, and the vertical axis is the coupling coefficient. Curves a, b, and c in the figure show the results of using edgewise winding, edgewise winding + uniform winding, and uniform winding spiral coils, respectively.

  From the figure, edgewise winding (curve a) and edgewise winding + uniform winding (curve b) have less change in the coupling coefficient with respect to the distance from the center axis A than the uniform winding (curve c), and the coupling coefficient is You can see that it is stable. Specifically, when the distance d is 2 cm, 4 cm, or 6 cm, the distance from the central axis A is about 6 cm or more, and the uniform winding (curve c) has a sharply reduced coupling coefficient, but the edgewise winding (Curve a) and edgewise winding + uniform winding (curve b) are almost constant or not as low as uniform winding (curve c). Accordingly, when the edge-wise winding or the edge-wise winding + uniform winding spiral coil 21a is used, the reception-side spiral coil 31a, that is, the location of the reception-side electronic device 3 is compared with the case where the uniform winding spiral coil 21a is used. It is possible to reduce the variation in power transmission due to. Note that, when the edgewise winding (curve a) is compared with the edgewise winding + uniform winding (curve b), a difference in characteristics can be seen. Therefore, it is possible to determine one of the selections based on this difference.

  In addition, the diameter of the transmission side spiral coil 21a in this experimental example is relatively small. However, the result of this experimental example is increased by increasing the diameter of the transmission side spiral coil 21a according to the scaling law. Can be applied to large ones.

  The wireless power transmission system according to the embodiment of the present invention has been described above. However, the present invention is not limited to that described in the above-described embodiment, and various modifications within the scope of the matters described in the claims. Design changes are possible. For example, the transmission-side spiral coil 21a in which the presence or absence of the electrical conductor 21aa or the line pitch g is different between the peripheral region N and the inner region M can be optimized according to the system. Alternatively, in addition to the edgewise winding and the uniform winding, for example, both or one of the peripheral region N and the inner region M is wound so as to gradually become denser toward the periphery, or in some cases, toward the periphery. It is also possible to wind it so that it gradually becomes sparse.

  In the present embodiment shown in FIG. 1, the transmission side coupling loop 22 is arranged on a different plane at a distance from the transmission side resonator 21, but the size of the transmission side coupling loop 22 is large. By selecting appropriately, it is possible to perform impedance matching while arranging the transmission-side resonator 21 and the transmission-side coupling loop 22 on the same plane. By doing so, the enlargement of the transmission-side electronic device 2 can be further suppressed. Similarly, in the present embodiment shown in FIG. 1, the reception side coupling loop 32 is arranged on a different plane at a distance from the reception side resonator 31, but the size of the reception side coupling loop 32 is large. By appropriately selecting the length, it is possible to perform impedance matching while arranging the reception-side resonator 31 and the reception-side coupling loop 32 on the same plane. By doing so, the receiving-end electronic device 3 can be further reduced in size.

DESCRIPTION OF SYMBOLS 1 Wireless power transmission system 2 Transmission side electronic device 21 Transmission side resonator 21a Transmission side spiral coil 21aa Transmission side spiral coil electric conductor 3 Reception side electronic device 31 Reception side resonator 31a Reception side spiral coil 31aa Electricity of reception side spiral coil Conductive wire 31b Capacitor M Inner region of transmission side spiral coil N Peripheral region of transmission side spiral coil g Line pitch of electric wire of transmission side spiral coil g 'Pitch of electric wire of reception side spiral coil

Claims (10)

A transmitting-side electronic device including a transmitting-side resonator having a transmitting-side spiral coil formed by spirally winding an electrical conductor, and
A receiving-side electronic device including a receiving-side resonator having a receiving-side spiral coil having a spiral diameter smaller than that of the transmitting-side spiral coil, wherein the electric conducting wire is flat and wound in a spiral shape; With
The transmission-side spiral coil is different from the peripheral region and the inner region located inside the peripheral region and including the center of the spiral in the presence or absence of the electrical conductors or the pitch between the lines.
The reception side spiral coil has the electric conductor wound more densely than the transmission side spiral coil,
The transmission-side resonator resonates at a predetermined resonance frequency, and the reception-side resonator resonates at the resonance frequency of the transmission-side resonator, whereby power is wirelessly transmitted from the transmission-side electronic device to the reception-side electronic device. A wireless power transmission system characterized by transmitting. The wireless power transmission system according to claim 1,
The wireless power transmission system, wherein the transmission-side spiral coil is provided with the electrical conductor only in the peripheral region. The wireless power transmission system according to claim 2,
The wireless power transmission system according to claim 1, wherein the transmitting-side spiral coil has a radial length of the peripheral region smaller than a radius of the inner region. The wireless power transmission system according to claim 3,
The wireless power transmission system according to claim 1, wherein a radial length of the peripheral region of the transmitting-side spiral coil is 1/6 or less of a radius of the inner region. The wireless power transmission system according to claim 1,
The transmitting-side spiral coil is continuously provided in the peripheral region and the inner region, and the electric conductor is densely wound in the peripheral region, and the electric conductor is sparse in the inner region. A wireless power transmission system characterized by being wound. The wireless power transmission system according to claim 5, wherein
The wireless power transmission system according to claim 1, wherein the transmitting-side spiral coil has a radial length of the peripheral region that is equal to or less than one-ninth of a radius of the inner region. The wireless power transmission system according to any one of claims 1 to 6,
2. The wireless power transmission system according to claim 1, wherein the transmitting side spiral coil is open at both ends resonating at a half wavelength. In the wireless power transmission system according to any one of claims 1 to 7,
The wireless power transmission characterized in that the receiving-side resonator has a line pitch of electric wires of the receiving spiral coil equal to or less than half of a line pitch of electric wires of the transmitting spiral coil. system. In the wireless power transmission system according to any one of claims 1 to 8,
The wireless power transmission system according to claim 1, wherein a capacitor is provided between both ends of the reception side spiral coil of the reception side resonator. The wireless power transmission system according to claim 9, wherein
The wireless power transmission system according to claim 1, wherein the reception side spiral coil has a diameter of 1/7 or less of the diameter of the transmission side spiral coil.

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