JP2014138509A - Resonator, and radio power feeding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio power feeding system which can achieve miniaturization and suppression of heat evolution in a resonator while maintaining excellent transmission efficiency when transmitting power between paired resonators by using a magnetic field resonance system.SOLUTION: Resonators 30 are used in a radio power feeding system for transmitting power on the basis of the magnetic field resonance method, and each resonator 30 is configured of a resonance coil (winding coil) 32 and a support member (support base) 31 for supporting the resonance coil 32. The resonance coil 32 converts AC power with a predetermined resonance frequency into electromagnetic field energy and vice versa. The support member 31 includes dielectric ceramic material as a main component. With this, dielectric loss and conductor loss can be suppressed when the paired resonators 30 are opposingly arranged in the radio power feeding system, and miniaturization and enhancement of the transmission efficiency of the resonator 30 can be achieved.

Description

  The present invention relates to a wireless power feeding system that uses a magnetic field resonance between resonators to transmit electric power from a power transmitting device to a power receiving device in a contactless manner.

  Conventionally, there is a demand for a wireless power feeding system that transmits power from a power transmission device to a power reception device in a contactless manner. As a technique for realizing a wireless power feeding system, a technique using electromagnetic induction, a technique using electromagnetic waves, and the like have been proposed. In recent years, as a technique applicable to a wireless power feeding system, a magnetic field resonance method in which electric power is transmitted from a power transmission device to a power reception device by using resonance of a magnetic field of a resonator has attracted attention. For example, Patent Document 1 discloses a basic concept of a magnetic field resonance method in which electric power is transmitted from one resonator to the other resonator by resonance of magnetic fields of two resonators arranged to face each other at a predetermined distance. ing. Further, for example, Non-Patent Document 1 has theoretically studied the maximum transmission efficiency obtained in the magnetic field resonance method, and it is possible to improve the transmission efficiency by increasing the Q value of each resonator. It is shown. Further, for example, Non-Patent Document 2 shows a technique for realizing a high Q value in a resonance coil as an antenna used in a magnetic field resonance method. Further, for example, in Patent Document 2, an electric vehicle or a plug-in hybrid vehicle is assumed as an application target of a wireless power feeding system, and a magnetic resonance method is used to provide a wireless power feeding system in a vehicle from a resonance coil disposed in a lower portion of the vehicle. A technique for transmitting power to a resonance coil is disclosed.

Special table 2009-501510 JP 2009-106136 A

Hidetoshi Matsuki, et al., “Frontiers of Contactless Power Transmission Technology”, CM Publishing, p. 7 (August 2009) Tomoyuki Fujieda, Masami Suzuki, “Examination of low-loss antenna for magnetic field resonance power transmission”, PIONEER R & D, Vol. 21, no. 1/2012, p. 11-15

  The resonator in the above-described wireless power feeding system includes, for example, a resonance coil using a winding coil such as a copper wire, and a support member having mechanical strength for ensuring the shape of the resonance coil. When a resonator having such a structure is installed in, for example, a vehicle, the installation space is limited. Therefore, it is desirable to make the resonator as small as possible. However, when a general resin material is used as the support member, it is necessary to increase the inductance value in order to ensure the high-frequency characteristics of the resonance coil, and the number of windings of the resonance coil increases, so that the size of the resonator is reduced. Cause trouble. Further, the material used as the support member acts as a dielectric and adds to the loss of the resonator. Furthermore, since the conductor loss inevitably increases as the line length of the resonance coil increases, heat generation caused by the dielectric loss and conductor loss of the resonance coil becomes a problem particularly when applied to a high-power wireless power feeding system. Such countermeasures against heat generation by the resonance coil require a structure for heat dissipation, which makes it more difficult to reduce the size. Moreover, it is not desirable from the viewpoint of effective use of electric energy that the transmission efficiency is reduced due to an increase in dielectric loss and conductor loss of the resonator. In addition, a decrease in transmission efficiency causes a disadvantage that the tolerance for mutual positional shifts is reduced in the resonators arranged to face each other. As described above, in the conventional wireless power feeding system using the magnetic field resonance method, it is difficult to transmit electric power with high transmission efficiency using a small-sized resonator that generates little heat.

  The present invention has been made to solve these problems, and an object of the present invention is to provide a wireless power feeding system that can reduce the size of a resonator and suppress heat generation, and can realize high transmission efficiency.

  In order to solve the above-described problems, a resonator according to the present invention is a resonator in a wireless power feeding system that transmits power from a power transmission side resonator to a power reception side resonator mainly using resonance of a magnetic field, A resonance coil that mutually converts alternating-current power and electromagnetic field energy at a resonance frequency, and a support member that includes a dielectric ceramic material as a main component and supports the resonance coil are configured.

  According to the resonator of the present invention, in the wireless power feeding system of the non-contact power transmission method (magnetic field resonance method) using the resonance of the magnetic field, the support for supporting the resonance coil constituting each resonator on the power transmission side and the power reception side. Since the member is made of a dielectric ceramic material as a main component, the increase in parasitic capacitance of the resonator makes it easy to ensure resonance characteristics, and the resonator can be downsized. Further, the dielectric loss can be suppressed by the low dielectric loss tangent characteristic of the dielectric ceramic. Further, since the conductor loss is reduced by shortening the line length of the resonance coil, the heat generation of the resonator due to the dielectric loss and conductor loss of the resonance coil can be suppressed. Furthermore, transmission efficiency between a pair of resonators is improved, waste of power energy is suppressed, and when a pair of resonators face each other at a relatively long distance or when a relatively large displacement occurs Even so, good power transmission can be maintained.

In the resonator of the present invention, it is desirable that the dielectric ceramic material constituting the support member has a relative dielectric constant εr of 8 or more and a dielectric loss tangent tan δ of 10 ⁻⁴ or less. If the relative dielectric constant εr of the dielectric ceramic material is less than 8, the resonant coil becomes large due to an increase in the number of turns of the resonant coil, and if the dielectric loss tangent tan δ of the dielectric ceramic material exceeds 10 ⁻⁴ , This is because transmission efficiency decreases due to an increase in body loss.

  In the resonator of the present invention, the support member can be formed in various structures. For example, you may employ | adopt the structure which has arrange | positioned the dielectric ceramic material in the electric field generation | occurrence | production part between the windings of a resonance coil. As a result, by disposing the dielectric ceramic material only in the electric field generating part that contributes to the characteristics of the resonance coil among the support members, the amount of the dielectric ceramic material can be reduced while ensuring the characteristics of the resonator. Cost can be reduced. In this case, a structure in which the electric field generating portion is filled with a powdered dielectric ceramic material may be employed. For example, if the support member is formed of a resin material and then processed to dispose the dielectric ceramic material, the amount of use of the dielectric material can be reduced while suppressing problems such as cracking of the support member. .

  The support member of the resonator of the present invention may be formed by adding a dielectric ceramic material to a resin material. Thus, the ratio of the dielectric ceramic material can be appropriately adjusted within a range in which the required characteristics of the resonator can be obtained, which is effective in reducing the material cost. Further, the support member of the resonator of the present invention may be formed of a dielectric ceramic material having a porous material. For example, if a plurality of through holes are formed in a region of the support base where the resonance coil is not formed, the amount of dielectric ceramic material used can be reduced according to the volume reduction of the support member.

  In order to solve the above-described problem, a wireless power feeding system according to the present invention is a wireless power feeding system that mainly transmits power from a power transmission device to a power reception device by using resonance of a magnetic field. A power source that supplies alternating-current power of a frequency, and a power-transmission-side resonator that resonates with the alternating-current power supplied from the power source and transmits the alternating-current power as electromagnetic energy, and the power receiving device includes the power transmission A power receiving side resonator that is coupled to the side resonance coil mainly by magnetic field resonance and receives the electromagnetic energy as AC power, and a circuit unit that operates by the AC power received by the power receiving side resonator. Each of the power transmitting side resonator and the power receiving side resonator includes a resonance coil that mutually converts the AC power and the electromagnetic field energy, and a dielectric ceramic material as a main component. , And a support member for supporting the resonance coil.

  According to the wireless power feeding system of the present invention, the resonator having the above characteristics can be applied to each of the power transmission side resonator of the power transmission device and the power reception side resonator of the power reception device. Therefore, in the power transmission device, the power transmission side resonator that resonates with the AC power supplied from the power supply transmits the electromagnetic field energy, and in the power reception device, the power reception side resonance is coupled with the power transmission side resonator mainly by the resonance of the magnetic field. The device receives the electromagnetic field energy and outputs AC power to the subsequent circuit unit. For example, the wireless power feeding system of the present invention can be used for various applications such as power supply to vehicles such as electric vehicles and plug-in hybrid vehicles, and power supply to information terminals such as mobile phones and notebook PCs. .

  In the wireless power feeding system of the present invention, the power transmission device is provided with a power transmission side matching circuit connected between the power source and the power transmission side resonator, and the power reception device is provided between the power reception side resonator and the circuit unit. A power-receiving-side matching circuit connected to may be provided. In this case, in the circuit unit of the power receiving device, a rectifier that rectifies AC power output from the power receiving side matching circuit and converts it to DC power, a capacitor that stores DC power output from the rectifier, and a capacitor that stores power. A load to which direct current power is supplied may be further provided.

  According to the present invention, when power is transmitted from the power transmission side resonator to the power reception side resonator mainly using the resonance of the magnetic field, the structure in which the resonance coil is supported by the support member containing the dielectric ceramic material as a main component is provided. By adopting it, it is possible to realize a wireless power feeding system that can reduce the size of the resonator and suppress the heat generation and can transmit power between the resonators with high transmission efficiency.

It is a block diagram which shows one structural example of the radio | wireless electric power feeding system to which this invention is applied. It is a figure which shows an example of the equivalent circuit of the power transmission side resonator and its related circuit part in a power transmission apparatus, and the power receiving side resonator and its related circuit part in a power receiving apparatus. It is a figure which shows the 1st structural example of the resonator of this embodiment. It is a figure which shows the 2nd structural example of the resonator of this embodiment. It is a figure which shows the 3rd structural example of the resonator of this embodiment. It is a figure which shows the 4th structural example of the resonator of this embodiment. It is a figure which shows the 5th structural example of the resonator of this embodiment. It is a figure which shows the 6th structural example of the resonator of this embodiment. It is a figure which shows the conditions of the simulation with respect to a pair of resonator. It is a graph which shows the characteristic of the transmission efficiency (eta) according to the material of a supporting member based on the simulation implemented on the conditions of FIG. FIG. 10 is a diagram illustrating a state in which a pair of resonators are displaced from the positions illustrated in FIG. 9 in a direction orthogonal to the respective central axes. FIG. 12 is a graph showing the relationship between the positional deviation amount P and the transmission efficiency η when a support member is not provided and when Teflon (registered trademark) and alumina are used for the support member based on the simulation performed in the state of FIG. 11. .

  Preferred embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below is an example of a form to which the technical idea of the present invention is applied, and the present invention is not limited by the content of the present embodiment.

  FIG. 1 is a block diagram showing a configuration example of a wireless power feeding system to which the present invention is applied. The wireless power feeding system illustrated in FIG. 1 is a system that transmits power from the power transmission device 1 to the power reception device 2 in a contactless (wireless) manner. For example, for a power receiving device 2 built in a vehicle, a wireless power feeding system that feeds power in a non-contact manner from a power transmitting device 1 arranged on the ground or road surface, or a power receiving device built in an information terminal such as a mobile phone or a notebook PC. A wireless power feeding system that feeds power to the device 2 in a non-contact manner from the power transmitting device 1 installed in the vicinity can be given.

  As shown in FIG. 1, the power transmission device 1 includes an AC / DC converter 10, a high frequency power source 11, a matching circuit 12, a power transmission side resonator 13, a wireless communication unit 14, and a control unit 15. Is done. The power receiving device 2 includes a power receiving resonator 20, a matching circuit 21, a rectifier 22, a battery 23, a load circuit 24, a wireless communication unit 25, and a control unit 26.

  In the power transmission device 1, the AC / DC converter 10 converts AC power from a commercial power source or the like into DC power. The high frequency power supply 11 is an oscillator that generates high frequency power of a predetermined frequency using DC power supplied from the AC / DC converter 10. The matching circuit 12 performs impedance matching between the output side of the high frequency power supply 11 that supplies high frequency power and the power transmission side resonator 13 in the subsequent stage. The power transmission side resonator 13 is a resonator that receives high frequency power supplied via the matching circuit 12 and resonates at a predetermined frequency to generate electromagnetic field energy. The specific structure and operation of the power transmission side resonator 13 will be described later.

  In the power receiving device 2, the power receiving resonator 20 is a resonator that is magnetically coupled to the power transmitting resonator 13 of the power transmitting device 1 and resonates at the predetermined frequency based on the magnetic field resonance to generate high frequency power. . In the present embodiment, the power reception side resonator 20 may basically have the same structure as the power transmission side resonator 13 of the power transmission device 1. The matching circuit 21 performs impedance matching between the power-receiving-side resonator 20 and the subsequent rectifier 22. The rectifier 22 rectifies the high-frequency power supplied via the matching circuit 21 and converts it into DC power. The battery 23 that functions as a storage battery is a secondary battery that stores electric power supplied via the rectifier 22. The load circuit 24 is a circuit that operates in accordance with the discharge current supplied from the battery 23, and various components included in the attachment target of the power receiving device 2 are assumed.

  On the other hand, the control unit 15 of the power transmission device 1 controls the overall operation of the power transmission device 1. Similarly, the control unit 26 of the power receiving device 2 controls the overall operation of the power receiving device 2. Each control unit 15 and 26 includes, for example, a processor that executes processing determined by the wireless power feeding system, and a memory that stores data and programs. In addition, the wireless communication unit 14 of the power transmission device 1 and the wireless communication unit 25 of the power reception device 2 are respectively connected to the control units 15 separately from the transmission of power between the power transmission side resonator 13 and the power reception side resonator 20 described above. 26 is a means for transmitting necessary information to each other wirelessly, and includes, for example, a transmission / reception circuit and an antenna.

  Next, the structure and operation of the power transmission side resonator 13 and the power reception side resonator 20 in the wireless power feeding system will be described with reference to FIG. In the present embodiment, each of the power transmission side resonator 13 and the power reception side resonator 20 includes a resonance coil that mutually converts AC power and electromagnetic field energy of a predetermined resonance frequency, and the power transmission side resonator 13 and the power reception side resonance. It is used in a state in which the container 20 is disposed facing each other at a relatively close distance and both are magnetically coupled. In such a state, magnetic field energy is mainly transmitted from the power transmission side resonator 13 to the power reception side resonator 20, and non-contact power transmission based on a so-called magnetic field resonance method becomes possible.

  FIG. 2 shows an example of an equivalent circuit of the power transmission side resonator 13 and the circuit portion related thereto in the power transmission device 1 and the power reception side resonator 20 and the circuit portion related thereto in the power reception device 2. In the power transmission device 1, the part of the series circuit of the oscillator 11a and the impedance Zo corresponds to the high frequency power supply 11 of FIG. 1, and the part of the parallel circuit of the inductance L and the capacitor C corresponds to the power transmission side resonator 13 of FIG. The two are connected via a resistor R1. In the power receiving device 2, the parallel circuit of the inductance L and the capacitance C corresponds to the power receiving side resonator 20 in FIG. 1, and a resistance is provided between the circuit portion and the load (battery 23 or load circuit 24 in FIG. 1). It is connected via R2. Thus, since the power transmission side resonator 13 and the power reception side resonator 20 are represented by the same equivalent circuit, they resonate (resonate) at the same resonance frequency by coupling of magnetic fields.

  In the power transmission side resonator 13 and the power reception side resonator 20, the inductance L is determined depending on the size and the number of turns of the resonance coil portion, and the capacitance C is determined depending on the parasitic capacitance (stray capacitance) between the wirings of the resonance coil. . In the equivalent circuit of FIG. 2, the circuit portions of the pair of power transmission side resonator 13 and the power reception side resonator 20 are expressed in the same manner as a circuit form in which a pair of coils generate electromagnetic induction. However, in the case of electromagnetic induction, since a magnetic material is used for the coil, the Q value becomes extremely low and transmission of power becomes difficult when the distance between the pair of coils is increased. Since the Q value of the resonance coil can be increased depending on the structure and material, even if the power transmission side resonator 13 and the power reception side resonator 20 are separated from each other to some extent, power can be efficiently transmitted by magnetic field coupling.

Here, the transmission efficiency η from the power transmission side resonator 13 to the power reception side resonator 20 is equivalently expressed by the form (figure of merit) of the following equation (1).
fom = k (Q1 · Q2) ^1/2 (1)
Where k: coupling coefficient Q1: Q value of resonance coil of power transmission side resonator 13 Q2: Q value of resonance coil of power reception side resonator 20

In the equation (1), the coupling coefficient k depends on the interval (air gap) between the resonance coils of the power transmission side resonator 13 and the power reception side resonator 20, and decreases as the interval increases. That is, the transmission efficiency η can be improved as the above-described Q1 and Q2 become higher with respect to a given coupling coefficient k according to the restrictions on the arrangement of the resonance coils. In general, the Q value of the resonance coil at the angular frequency ω is given by equation (2).
Q = ωL / r (2)
Where L: inductance r: resistance

  In the equation (2), the resistance r is represented by the sum of dielectric loss, conductor loss, and radiation loss. Among these, in this embodiment, in particular, the Q value of the resonance coil is improved by reducing the dielectric loss and the conductor loss by devising the structures and materials of the power transmission side resonator 13 and the power reception side resonator 20. However, details will be described later.

  Next, the structure of the power transmission side resonator 13 and the power reception side resonator 20 of FIG. 1 is demonstrated. As described above, since the basic structures of the power transmission side resonator 13 and the power reception side resonator 20 are the same, in the following, a resonator 30 that is compatible with both the power transmission side resonator 13 and the power reception side resonator 20 is assumed. Will be described. First, a first structural example of the resonator 30 of this embodiment will be described with reference to FIG. As shown in FIG. 3, the resonator 30 according to the first structural example includes a support base 31 (support member of the present invention) made of a dielectric ceramic material and a spiral winding made of a conductor on the support base 31. It is comprised with the coil 32 (resonance coil of this invention).

In the first structural example, the support base 31 is a member obtained by processing a ceramic material having a high dielectric constant into a flat plate shape. For example, a dielectric ceramic material such as alumina or an ε34 material (representing a ceramic material having a relative dielectric constant εr = 34; hereinafter the same) can be used. As the dielectric ceramic material used for the support base 31, it is desirable to use a material having a relative dielectric constant εr of 8 or more and a dielectric loss tangent tan δ of 10 ⁻⁴ or less. This reflects the result of evaluating the dependence of the transmission efficiency η on the dielectric ceramic material, which will be described later in detail. Further, since the support base 31 has a role of supporting the entire resonator 30, it is desirable that the support base 31 be formed to a thickness that can ensure a certain shape of the winding coil 32 and obtain sufficient mechanical strength.

  On the other hand, the spiral winding coil 32 is disposed on the upper surface of the support base 31 and may be placed in a state where, for example, a linear conductor is wound on the support base 31, or the surface of the support base 31. You may metallize and form. The winding coil 32 may be formed on the inner layer of the support base 31 without being limited to the surface of the support base 31. The size and the number of turns of the winding coil 32 can be appropriately determined according to the resonance frequency and the Q value. In the present embodiment, since a ceramic material having a high dielectric constant is used for the support base 31, the winding coil 32 can be formed in a small size with respect to a necessary Q value.

  Next, a second structural example of the resonator 30 of this embodiment will be described with reference to FIG. As shown in FIG. 4, the resonator 30 according to the second structural example includes a support member 33 made of a dielectric ceramic material, and a helical winding coil 34 formed on the side surface of the support member 33 (the present invention). Resonance coil). In the second structural example, the support member 33 is a member obtained by processing a dielectric ceramic material similar to the support base 31 of the first structural example into a cylindrical shape. On the other hand, the helical winding coil 34 is disposed on the cylindrical side surface of the support member 33 and can be formed by the same method as the winding coil 32 of the first structural example. Also in the second structure example, the size and the number of turns of the winding coil 34 can be appropriately determined according to the resonance frequency and the Q value.

  3 and 4, both ends of the winding coils 32 and 34 of the resonator 30 may be opened (open) or may be connected to circuit elements. In order to supply power to the resonator 30 in a state where both ends of the winding coils 32 and 34 are open, for example, power may be supplied to the resonator 30 via a loop element disposed in the vicinity. Further, with respect to the resonator 30, a capacitor may be connected in series to one end of the winding coils 32 and 34, or a capacitor may be connected in parallel to both ends of the winding coils 32 and 34. By appropriately setting the capacitance value of such a capacitor, the resonance frequency and Q value of the resonator 30 can be adjusted.

  Each of the first and second structural examples is an example of the resonator 30 of the present embodiment. As long as desired resonance characteristics can be obtained, dielectric ceramic materials are loaded on the resonant coils having various structures. The resonator 30 having the structure described above can be employed. Although the basic effects of the first and second structural examples are common, there are some differences from the viewpoint of reducing the size of the resonator 30. In other words, the first structure example is suitable for reducing the thickness of the resonator 30 because the spiral wound coil 32 can be formed in the same plane. On the other hand, since the second structural example can be configured by applying the number of turns of the helical winding coil 34 in the height direction, it is suitable for downsizing the resonator 30 in plan view.

  A feature of the resonator 30 of the present embodiment including the first and second structural examples is that the resonant coil is supported by a support member including a dielectric ceramic material as a main component. Here, when the resonator 30 of the present embodiment is applied to the equivalent circuit of FIG. 2, the value of the inductance L (FIG. 2) is determined according to the line length of the winding coils 32 and 34, and the capacitance C (FIG. 2). ) Is determined according to the parasitic capacitance of the region (electric field generating portion) between the adjacent wires of the winding coils 32 and 34. If a dielectric ceramic material having a high dielectric constant is loaded in the vicinity of the winding coils 32 and 34, the parasitic capacitance can be increased. As a result, since the inductance L when the resonator 30 is resonated at a predetermined resonance frequency can be reduced, the resonator 30 can be downsized by reducing the number of turns of the winding coils 32 and 34. In particular, in applications where the resonator 30 is provided in a vehicle or the like, the installation space of the resonator 30 is restricted, so that downsizing of the resonator 30 has a great merit.

  Next, another structural example mainly focusing on the structure of the support base 31 will be described based on the first structural example of FIG. FIG. 5 shows a third structural example of the resonator 30 of the present embodiment. Among the resonators 30 according to the third structural example, FIG. 5A shows a top view, and FIG. 5B shows a side cross-sectional view taken along the line aa of FIG. The resonator 30 according to the third structure example includes a spiral wound coil 32 similar to that of the first structure example, and a support base 35 having a shape different from that of the first structure example. Specifically, the support base 31 (FIG. 3) of the first structure example is flat, whereas the support base 35 of the third structure example is processed into a disk shape having an opening 35a in the center. It is a member. As the material of the support base 35, the same dielectric ceramic material as that in the first structural example can be used.

  The third structure example is obtained by removing a region that does not face the winding coil 32 from the support base 31 of the first structure example, and has a circular planar shape along the outer peripheral side of the winding coil 32. And a circular opening 35 a along the inner peripheral side of the winding coil 32. Thereby, only the area | region which opposes the electric field generation | occurrence | production part between each line | wire of the winding coil 32 is set as the structure which opposes a dielectric ceramic material, The dielectric material in the support stand 35 is maintained, maintaining the high frequency characteristic of the winding coil 32. The amount of ceramic material used can be reduced as much as possible. In other words, the support base 35 of the third structural example has a dielectric material equivalent to the total area of the four corner regions and the central opening 35a that do not face the electric field generating portion, compared to the support base 31 of the first structural example. The amount of ceramic material used is reduced, which is effective in reducing material costs.

  FIG. 6 is a diagram illustrating a fourth structure example of the resonator 30 according to the present embodiment. FIG. 6A shows a top view of the resonator 30 according to the fourth structure example, and FIG. 6B shows a side cross-sectional view taken along the line aa of FIG. 6A. The resonator 30 according to the fourth structure example includes a spiral wound coil 32 similar to that of the first structure example, and a support base 36. A feature of the fourth structure example is that the flat support base 36 is a composite member having a region 36a made of a resin material and a region 36b made of a dielectric ceramic material. The region 36a has a structure in which the region 36b having the same shape as the support base 35 (FIG. 5) of the third structure example is partially removed. As shown in FIG. The dielectric ceramic material (sintered body) is filled in a solidified state. And the winding coil 32 is arrange | positioned in the part of the interface of the resin material of the area | region 36a, and the dielectric ceramic material of the area | region 36b.

  6 illustrates the case where the region 36a is made of a resin material, the region 36a may be formed of a material other than the resin material as long as the region 36b can be filled with the powdered dielectric ceramic. . Further, although not shown in FIG. 6B, a flat lid member made of a resin material or the like covering the area 36b may be provided.

  According to the resonator 30 according to the fourth structure example, the dielectric ceramic material is disposed opposite to the electric field generating portion of the winding coil 32 as in the third embodiment, so that good high frequency characteristics can be maintained. However, the amount of dielectric ceramic material used can be reduced as compared with the first structural example. Further, in the fourth structure example, compared to the third structure example, the support base 36 is formed using a resin material and a powdery dielectric ceramic material, which causes problems such as cracking of the dielectric ceramic material. The structure is difficult, and the strength of the resonator 30 can be improved.

  Next, a fifth structure example of the resonator 30 of this embodiment will be described with reference to FIG. In the fifth structural example, the basic structure of the resonator 30 is the same as that of the first structural example (FIG. 3), but a support base 37 having a composition different from that of the support base 31 of the first structural example is used. Yes. FIG. 7A is a partially enlarged plan view of the support base 37 of the fifth structural example. The support base 37 of the fifth structural example is formed of a material obtained by adding a filler-like dielectric ceramic material 37b to a resin material 37a. In the example of FIG. 7A, each filler of the dielectric ceramic material 37b exists independently. The dielectric constant of the support base 37 is a predetermined value corresponding to the component ratio of the resin material 37a and the dielectric ceramic material 37b. By adopting the fifth structural example, the ratio of the dielectric ceramic material 37b occupying the volume of the support base 37 can be suppressed, which is effective in reducing the material cost.

  FIG. 7B is a modification of the fifth structural example, and is similar to FIG. 7A in that a filler-like dielectric ceramic material 37b is added to the resin material 37a. The state of the ceramic material 37b is different. That is, in the example of FIG. 7B, the individual fillers of the dielectric ceramic material 37b exist in a state of being connected to each other. According to the verification by the inventors, the dielectric constant of the support base 37 when the component ratio of the resin material 37a and the dielectric ceramic material 37b is constant is the dielectric constant of the resin material 37a in the example of FIG. In the example of FIG. 7B, it was confirmed that the dielectric constant of the dielectric ceramic material 37b was dominant. Therefore, in order to increase the dielectric constant of the support base 37 as much as possible, it is advantageous to employ FIG.

  Next, a sixth structural example of the resonator 30 of the present embodiment will be described with reference to FIG. Of the resonator 30 according to the sixth structural example, FIG. 8A shows a top view, and FIG. 8B shows a side cross-sectional view taken along the line aa in FIG. 8A. The resonator 30 according to the sixth structure example includes a spiral winding coil 32 similar to the first structure example, and a support base 38. A feature of the sixth structural example is that a support base 38 having a porous structure is used. Specifically, as shown in FIG. 8A, a plurality of through holes 38a are formed in a disk-shaped support base 38 having the same shape as that of the third structural example. As shown in FIG. 8B, the plurality of through holes 38a penetrate the support base 38 in the stacking direction with a predetermined diameter in the region of the support base 38 where the winding coil 32 is not disposed.

  By employing the sixth structure example, the amount of the dielectric ceramic material used can be further reduced in accordance with the volume reduction of the support base 38 as compared with the third structure example. Note that the number, position, diameter, and the like of the plurality of through holes 38 a are not limited to the example of FIG. 8, and can be appropriately set according to the amount of dielectric ceramic material used and the strength of the support base 38. Further, the sixth structure example is not limited to a structure in which a plurality of through holes 38a are provided, and a support base 38 having various porous structures having a structure in which a dielectric ceramic material is partially removed can be employed. . Furthermore, in the sixth structural example, the support base 38 having a porous structure may be configured by using porous ceramics as the dielectric ceramic material.

  As described above, the third to sixth structure examples have been described based on the case where the third to sixth structure examples are applied to the first structure example in FIG. 3. However, the third to sixth structure examples are illustrated in FIG. It is also possible to apply to the example of the structure. However, with regard to the third and fourth (FIGS. 5 and 6) structural examples, the winding coil 34 is mainly adjusted by adapting the size of the winding coil 34 in FIG. 4 and the height of the cylinder of the support member 33. It is possible to easily realize a shape in which the support member 33 is disposed only in a region facing the electric field generating portion.

  Next, specific characteristics and effects in the case where power is transmitted using a pair of resonators 30 in the wireless power feeding system of the present embodiment will be described. In the following, a state in which a pair of resonators 30 are arranged to face each other at a predetermined distance and power of a predetermined resonance frequency is transmitted is modeled, and then a transmission characteristic is verified by performing an electromagnetic field simulation. . FIG. 9 shows the simulation conditions for the pair of resonators 30. As shown in FIG. 9, the pair of resonators 30 is assumed to have a structure using the helical winding coil 34 of FIG. 4, and the support member 33 is not shown. The pair of resonators 30 were tested for transmission characteristics in a state where the center axes of the pair of resonators 30 are aligned with each other by a distance L. Note that one of the pair of resonators 30 is the power transmission side resonator 13, and the other is the power reception side resonator 20. The winding coil 34 of each resonator 30 has a diameter D and an interval S between the windings. For example, it is assumed that D = 600 mm and S = 38 mm and the distance L is changed.

  Table 1 below shows the dielectric constant ε and the dielectric loss tangent tan δ for the four materials assumed as the support member 33 of each resonator 30, and the number n of turns of the winding coil 34 in the above simulation. Shown in comparison.

  In Table 1, as a resin material, in addition to a general resin (resin A), Teflon (resin B; “Teflon” is a registered trademark) whose dielectric constant is lower than this is listed, and as a ceramic material, alumina ( Ceramic A) and ε34 material (ceramic B) having a higher dielectric constant. Therefore, the relative dielectric constant εr increases in the order of the resins B, A, and ceramics A and B, and the dielectric loss tangent tan δ decreases in the order of the resins A, B, and ceramics A and B. Further, the number of turns n of the winding coil 34 made of a ceramic material is reduced as compared with the resin material. In addition, the number of turns n in the case of only the winding coil 34 without providing the support member 33 was n = 5.25. Further, specifically, for example, polyacetal or glass epoxy substrate was used as the general resin.

  In Table 1, as the relative dielectric constant εr increases, the number of turns n of the winding coil 34 decreases, as described with reference to FIG. 2, as the relative dielectric constant ε increases, the capacitance C of the winding coil 34 increases. This is because it increases. That is, when the winding coil 34 is designed, assuming that the diameter D and the spacing S between the windings are common, the winding coil 34 can resonate at a predetermined resonance frequency with a relatively small number of turns n. Because. In this case, the size of the support member 33 can be relatively reduced as the number of turns n of the winding coil 34 decreases.

  FIG. 10 is a graph showing the characteristics of the transmission efficiency η according to the material of the support member 33 based on the simulation performed under the conditions of FIG. In FIG. 10, in addition to the support member 33 using the four types of materials shown in Table 1, the characteristics L1 to S5 of the distance L and the transmission efficiency η in FIG. 9 are compared with the case where the support member 33 is not provided. doing. In general, as described using the above equation (1), when the distance L between the pair of resonators 30 increases, the transmission efficiency η also decreases as the coupling coefficient k decreases. As shown in FIG. 10, it can be seen that the characteristic S3 when the general resin is used for the support member 33 has the greatest deterioration in the transmission efficiency η even if the characteristic S1 when the support member 33 is not provided is included. . This is presumed to be due to an increase in the dielectric loss of the resonator 30 because the general resin mainly has a large dielectric loss tangent tan δ.

It can also be seen that the characteristic S5 when Teflon is used for the support member 33 is similar to the characteristic S1 when the support member 33 is not provided. On the other hand, it can be seen that both the characteristic S2 when alumina is used for the support member 33 and the characteristic S4 when ε34 material is used for the support member 33 can ensure high transmission efficiency η. Considering the actual use form of the wireless power feeding system, for example, when the distance L = 400 mm, the characteristics that can ensure the transmission efficiency η = 90% are desirable. In FIG. 10, this condition is satisfied only when the support member 33 is made of alumina or ε34. Although it has already been described that the dielectric ceramic material used for the support member 33 is preferably a relative dielectric constant εr of 8 or more and a dielectric loss tangent tan δ of 10 ⁻⁴ or less, this is also supported by the results of FIG.

  Next, the influence on the transmission efficiency η when the positional deviation of the pair of resonance coils 30 occurs under the conditions of FIG. FIG. 11 shows a state in which a pair of resonators 30 similar to FIG. 9 are displaced from each other in the direction orthogonal to the central axis from the position shown in FIG. 9 (position displacement amount P). It is desirable that the positional deviation as shown in FIG. 11 can be tolerated to some extent in consideration of the usage pattern of the wireless power feeding system. On the other hand, FIG. 12 shows the relationship between the displacement P and the transmission efficiency η when the support member 33 is not provided and when Teflon and alumina are used for the support member 33 based on the simulation performed in the state of FIG. It is shown as a graph.

  As shown in FIG. 12, when the support member 33 is not provided and when Teflon is used for the support member 33, the transmission efficiency η deteriorates to the same extent when the positional deviation amount P increases. On the other hand, when alumina is used for the support member 33, it is understood that the deterioration of the transmission efficiency η is reduced when the positional deviation amount P is increased. For example, in FIG. 12, when the transmission efficiency η = 94% is considered as a reference, when the support member 33 is not provided and when Teflon is used for the support member 33, P = 120 mm, which is lower than the reference. It can be seen that when alumina is used for the member 33, it is below the reference when P = 350 mm is reached. That is, by using alumina for the support member 33, it is possible to increase the positional deviation amount P allowed for the pair of resonators 30 to nearly three times as compared with other conditions. The use of a ceramic material having a high dielectric constant, such as alumina, for the support member 33 improves the overall transmission efficiency η of the pair of resonators 30, and in addition to the effect of strengthening lateral displacement. Even if the distance L between the pair of resonators 30 is increased, there is an effect that high efficiency can be maintained.

  The contents of the present invention have been specifically described above based on the present embodiment, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, the configuration example of FIG. 1 is shown as the wireless power supply system of the present embodiment, but the present invention is not limited to this, and as long as the resonator having the structural features of the present invention is used, wireless power supply having various configurations is possible. The present invention can be applied to a system. In addition to the alumina and ε34 materials described in this embodiment, various materials can be used as the dielectric ceramic material included in the resonator support member as long as good transmission efficiency η can be secured. . Further, as the application of the wireless power supply system to which the present invention can be applied, the power supply to the vehicle and the power supply to the information terminal have been mentioned. For example, TV, home appliances, lighting equipment, game equipment, medical equipment, industrial equipment The present invention can be applied to wireless power feeding systems for various uses.

DESCRIPTION OF SYMBOLS 1 ... Power transmission apparatus 2 ... Power reception apparatus 10 ... AC / DC converter 11 ... High frequency power supply 12 ... Matching circuit 13 ... Power transmission side resonator 14 ... Wireless communication part 15 ... Control part 20 ... Power reception side resonator 21 ... Matching circuit 22 ... Rectifier DESCRIPTION OF SYMBOLS 23 ... Battery 24 ... Load circuit 25 ... Wireless communication part 26 ... Control part 30 ... Resonator 31, 35, 36, 37, 38 ... Support stand 32, 34 ... Winding coil 33 ... Support member

Claims (10)

A resonator in a wireless power feeding system that mainly uses magnetic field resonance to transmit power from a power transmitting resonator to a power receiving resonator,
A resonant coil that mutually converts AC power and electromagnetic energy of a predetermined resonant frequency;
A support member that includes a dielectric ceramic material as a main component and supports the resonant coil;
A resonator comprising: The resonator according to claim 1, wherein the dielectric ceramic material has a relative dielectric constant εr of 8 or more and a dielectric loss tangent tan δ of 10 ⁻⁴ or less.   3. The resonator according to claim 1, wherein the support member has a structure in which the dielectric ceramic material is disposed in an electric field generating portion between windings of the resonance coil.   The resonator according to claim 3, wherein the electric field generator has a structure in which the dielectric ceramic material in powder form is filled.   The resonator according to any one of claims 1 to 3, wherein the support member is formed by adding the dielectric ceramic material to a resin material.   The resonator according to any one of claims 1 to 3, wherein the support member is made of the dielectric ceramic material having a porous structure. A wireless power feeding system that mainly uses magnetic field resonance to transmit power from a power transmitting device to a power receiving device,
The power transmission device is:
A power supply for supplying AC power of a predetermined frequency;
A power transmission-side resonator that resonates with the AC power supplied from the power source and transmits the AC power as electromagnetic energy;
With
The power receiving device is:
A power receiving side resonator coupled with the power transmitting side resonance coil mainly by resonance of a magnetic field and receiving the electromagnetic field energy as AC power;
A circuit unit that operates by the AC power received by the power-receiving-side resonator;
With
Each of the power transmission side resonator and the power reception side resonator is:
A resonant coil that mutually converts the AC power and the electromagnetic field energy;
A support member that includes a dielectric ceramic material as a main component and supports the resonant coil;
A wireless power feeding system comprising: The wireless power feeding system according to claim 7, wherein the dielectric ceramic material has a relative dielectric constant εr of 8 or more and a dielectric loss tangent tan δ of 10 ⁻⁴ or less. A power transmission side matching circuit connected between the power source and the power transmission side resonator;
A power receiving side matching circuit connected between the power receiving side resonator and the circuit unit;
The wireless power feeding system according to claim 7 or 8, further comprising: The circuit section is
A rectifier that rectifies the AC power output from the power receiving side matching circuit and converts the AC power into DC power;
A battery for storing the DC power output from the rectifier;
A load to which the DC power stored in the capacitor is supplied;
The wireless power feeding system according to claim 9, comprising: