JP2013031272A - Radio power transmission device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the distance between adjacent resonators within a radio power transmission device a long range while preventing the device from becoming larger and power transmission efficiency from declining.SOLUTION: A radio power transmission device 1 comprises: a power transmitter 100 including a resonator train 110 formed by a plurality of resonators 102 having nearly equal resonance frequencies resonating through an electric field or a magnetic field and becoming a series coupling state, and an input part 120 for supplying power with a frequency of a frequency component nearly equal to the resonance frequencies to one end of the resonator train 110; a power receiver 200 including a resonator train 210 formed by a plurality of resonators 202 having resonance frequencies nearly equal to the resonance frequencies of the resonators 102 resonating through an electric field or a magnetic field and becoming a series coupling state, and an output part 220 for taking out power transmitted from the power transmitter 100 from one end of the resonator train 210. A resonator RFsituated at an end different than the end within the resonator train 110 and a resonator RFsituated at an end different than the end within the resonator train 210 resonate through an electric field or a magnetic field and become a series coupling state.

Description

  The present invention relates to a wireless power transmission apparatus and method, and more particularly, to a wireless power transmission apparatus and method for transmitting power using a resonance phenomenon between resonators.

  Research on a wireless power transmission device that arranges two resonators and transmits power using a resonance phenomenon caused by electromagnetic coupling between the two resonators has been actively conducted. An example of a wireless power transmission device is described in Non-Patent Document 1. As described in Non-Patent Document 1, the circuit is the same as a direct-coupled resonator band-pass filter. The repeater described below is a resonator disposed between input and output except for the resonators at both ends. Corresponding to

  However, in the resonator direct connection type bandpass filter, as described in Non-Patent Document 2, in order to prevent downsizing and coupling other than between adjacent resonators, the spread of the near electromagnetic field created by the resonator is reduced. The design has been made with a policy to suppress. On the other hand, in a wireless power transmission device, it is important in application to extend the power transmission distance, and it is important to widen the near electromagnetic field distribution created by the resonator. That is, although it can be explained by the same theory, the problems are different, and a new concept is required for the development of a wireless power transmission device.

  In the wireless power transmission device, the power transmission efficiency decreases as the distance between the resonators increases. Techniques for suppressing this reduction in transmission efficiency and realizing long-distance power transmission are disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2010-219838), Patent Document 2 (Japanese Patent Laid-Open No. 2010-148273), and Patent Document. 3 (Japanese Unexamined Patent Application Publication No. 2010-158114) and Japanese Patent Application Laid-Open No. 2010-246248 (Japanese Unexamined Patent Application Publication No. 2010-246248). The technology disclosed in the above publication describes that a repeater is inserted between the power transmission side resonator and the power reception side resonator.

  In addition, in Patent Document 5 (Japanese Translation of PCT International Publication No. 2010-537496), there is a description that a repeater called a parasitic circuit operates as a short-distance hop and substantially becomes a large number of transmitters. Are arranged in parallel, and are not intended to increase the distance by arranging the resonators according to the present invention in series. In addition, the repeater described in Patent Document 6 (Japanese Patent Publication No. 2010-520716) is not a passive resonator inserted between the power transmission side resonator and the power reception side resonator, but frequency conversion, etc., similar to the relay in wireless communication. It is an actively operated repeater that is capable of performing the above and is different from the repeaters described in other publications.

  Patent Document 1 (Japanese Patent Laid-Open No. 2010-219838), Patent Document 2 (Japanese Patent Laid-Open No. 2010-148273), Patent Document 3 (Japanese Patent Laid-Open No. 2010-158114), Patent Document 4 (Japanese Patent Laid-Open No. 2010-246248) The effect of the repeater described in (1) is as follows. Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-219838) describes that the distance between the power transmitter and the power receiver can be increased without significantly reducing the power transmission efficiency. In Patent Document 2 (Japanese Patent Laid-Open No. 2010-148273), the transmission efficiency can be improved while keeping the distance between the power transmitter and receiver constant, or the distance between the power transmitter and the power receiver is increased in paragraph [0024]. It is described that a repeater is used.

Patent Document 3 (Japanese Patent Laid-Open No. 2010-158114) also describes that the distance between the power transmitter and the power receiver can be increased as an effect of the repeater. Also in Patent Document 4 (Japanese Patent Laid-Open No. 2010-246248), a repeater called a passive repeater increases the access distance, that is, the distance between the power transmitter and the power receiver, as described in paragraph [0015] and FIG. It is described as being used to do. As described above, Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-219838), Patent Document 2 (Japanese Patent Application Laid-Open No. 2010-148273), Patent Document 3 (Japanese Patent Application Laid-Open No. 2010-158114), and Patent Document 4 (Japanese Patent Application Laid-Open Publication No. The role of the repeater described in Japanese Patent Application Laid-Open No. 2010-246248), that is, the resonator, was to lengthen the entire length of the device including the power transmitter and the power receiver in a state in which a decrease in power transmission efficiency was suppressed.
As described above, in the technique described in the above-described document, it is possible to lengthen the entire length of the apparatus including the power transmitter and the power receiver by installing the repeater in a state in which a decrease in power transmission efficiency is suppressed.

JP 2010-219838 A JP 2010-148273 A JP 2010-158114 A JP 2010-246248 A Special table 2010-537496 gazette Special table 2010-520716

Sakurai, et al., “Comparative Study of Resonators Used for Resonant Wireless Power Transmission”, IEICE Technical Report WPT2010-01, The Institute of Electronics, Information and Communication Engineers, April 2010, p. 1-7 Ma and 2 others, “Comparative study of characteristics of six types of microstrip spiral resonators”, IEICE Technical Report MW2002-70, The Institute of Electronics, Information and Communication Engineers, September 2002, p. 1-5

  In the technology described in the above-mentioned document, there is a restriction that a repeater must be installed between the power transmitter and the power receiver. Therefore, the repeater cannot be installed and long distance transmission must be performed only by radio. There was a problem that it was not considered.

  The object of the present invention is to prevent the distance between adjacent resonators in the wireless power transmission device, particularly between the power transmitter and the power receiver, while suppressing the decrease in power transmission efficiency when the repeater, which is the problem described above, cannot be installed. An object of the present invention is to provide a wireless power transmission apparatus and method that solves the problem that the distance between adjacent resonators cannot be increased.

The wireless power transmission device of the present invention is
A power transmitter, and a power receiver that extracts power transmitted from the power transmitter,
The power transmitter
A first resonator array in which at least two resonators having substantially the same resonance frequency resonate through an electric field or a magnetic field generated by the resonator and are coupled in series;
An input unit that generates power having a frequency component whose frequency is substantially the same as the resonance frequency, and supplies the generated power to one end of the first resonator array;
The power receiver
A second resonator array in which at least two resonators having substantially the same resonance frequency as the resonance frequency resonate through an electric field or a magnetic field generated by the resonator and are coupled in series;
An output unit that extracts the power transmitted from the power transmitter from one end of the second resonator array;
Of the first resonator row of the power transmitter, the resonator at the other end located at a different end from the one end connected to the input unit, and the second resonator row of the power receiver, A resonator at the other end located at an end different from the one end connected to the output unit is resonated through an electric field or a magnetic field to form a coupled state in series.

The wireless power transmission method of the present invention includes:
A power transmitter including a first resonator array including at least two resonators having substantially the same resonance frequency, and an input provided at one end of the first resonator array; and the resonance frequency and the resonance frequency. A power receiver including: a second resonator array including at least two resonators substantially identical to each other; and an output unit that extracts power transmitted from the power transmitter from one end of the second resonator array; Provided,
The first resonator array of the power transmitter is resonated through an electric field or a magnetic field generated by the resonator to be in a series coupled state,
The input unit of the power transmitter generates power having a frequency component whose frequency is substantially the same as the resonance frequency,
The input of the power transmitter supplies the generated power to one end of the first array of resonators;
Of the first resonator row of the power transmitter, the resonator at the other end located at a different end from the one end connected to the input unit, and the second resonator row of the power receiver, Resonating through the electric field or magnetic field with the resonator at the other end located at a different end from the one end connected to the output unit, in a series coupled state,
The output unit of the power receiver extracts the power transmitted from the power transmitter from the one end of the second resonator array.

  As mentioned above, although the structure of this invention was demonstrated, this invention is not restricted to this, Various aspects are included. It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between a method, an apparatus, a system, etc. are also effective as an aspect of the present invention.

  The various components of the present invention do not necessarily have to be independent of each other. A plurality of components are formed as a single member, and a single component is formed of a plurality of members. It may be that a certain component is a part of another component, a part of a certain component overlaps with a part of another component, or the like.

  Moreover, although the several procedure is described in order in the method of this invention, the order of the description does not limit the order which performs a several procedure. For this reason, when implementing the method of this invention, the order of the several procedure can be changed in the range which does not interfere in content.

  Further, the plurality of procedures of the method of the present invention are not limited to being executed at different timings. For this reason, another procedure may occur during the execution of a certain procedure, or some or all of the execution timing of a certain procedure and the execution timing of another procedure may overlap.

  ADVANTAGE OF THE INVENTION According to this invention, while suppressing the enlargement of an apparatus and suppressing the fall of electric power transmission efficiency, between adjacent resonators in a wireless power transmission device, especially between adjacent resonators between a power transmitter and a power receiver. Provided are a wireless power transmission apparatus and method capable of increasing the distance.

It is a block diagram which shows typically the structure of the wireless power transmission apparatus which concerns on embodiment of this invention. It is a block diagram which shows typically the response | compatibility of the parameter for analyzing the wireless power transmission apparatus which concerns on embodiment of this invention by calculation of a transfer function. It is a figure which shows the distance dependency between resonators of a coupling coefficient. It is a figure which shows the minimum value of a coupling coefficient with respect to the number of resonators of the wireless power transmission apparatus which takes a Butterworth type of 1% of a specific band. It is a figure which shows the maximum value of the power transmission efficiency with respect to the number of resonators of the wireless power transmission apparatus which takes a Butterworth type of 1% of a specific band. It is a figure which shows the relationship of the value which remove | divided the power transmission efficiency with the minimum value of the coupling coefficient with respect to the number of resonators of the wireless power transmission apparatus of Butterworth type of 1% of a specific band. 1 is a block diagram schematically showing a wireless power transmission device according to an embodiment of the present invention. In a wireless power transmission device of Butterworth type with a relative bandwidth of 1%, it is a diagram showing the relationship of the maximum value within the pass band of power transmission efficiency for a combination of resonators having different unloaded Q values. In the Example of the wireless power transmission apparatus of this invention, it is a figure which shows the relationship of the maximum value in the pass band of the power transmission efficiency with respect to the combination of the unloaded Q value of four resonators.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

(First embodiment)
FIG. 1 is a block diagram schematically showing a configuration of a wireless power transmission device 1 according to an embodiment of the present invention.
As shown in FIG. 1, the wireless power transmission device 1 according to the embodiment of the present invention includes a power transmitter 100 and a power receiver 200 that extracts power transmitted from the power transmitter 100. At least two resonators 102 (resonator RF ₁ , resonator RF _n , where n is an integer of 2 or more) having substantially the same resonance frequency resonate through an electric field or a magnetic field generated by the resonator 102 and are connected in series. the first resonator column 110 as a combined state, the generated power P _i to generate a power P _i frequencies consisting resonant frequency and substantially the same frequency components of the first resonator column 110 The power receiver 200 includes at least two resonators 202 (resonator RF _{n + 1} and resonator RF _{n + m} ) having substantially the same resonance frequency as the resonance frequency of the resonator 102. , Where m is an integer of 2 or more) and resonates through the electric field or magnetic field generated by the resonator 202 to be coupled in series, and the power P transmitted from the power transmitter 100 and at least an output unit 220 for extracting _o from one end 212 of the second resonator array 210, and an end portion different from the one end 112 connected to the input unit 120 in the first resonator array 110 of the power transmitter 100. resonator 102 at the other end 114 located at the (cavity RF _n) and, in the second resonator column 210 of the power receiver 200, the other end 214 located at the end different from the end 212 connected to the output unit 220 The resonator 202 (resonator RF _{n + 1} ) is resonated through an electric field or a magnetic field to be coupled in series.

In the wireless power transmission device 1 according to the embodiment of the present invention, it is preferable that both the number of the resonators 102 of the power transmitter 100 and the number of the resonators 202 of the power receiver 200 are equal. That is, n = m. Hereinafter, the resonator 102 or the resonator 202 is referred to as a resonator RF ₁ , a resonator RF _n , a resonator RF _{n + 1} , or a resonator RF _{n + m} when it is necessary to distinguish each resonator. When there is no need to do this, the resonator 102 or the resonator 202 is called.

  In the following drawings, the configuration of parts not related to the essence of the present invention is omitted and is not shown.

The resonator 102 and the resonator 202 can be configured using a coil, for example. Although the kind of coil is not specifically limited, For example, they are a spiral coil, a solenoid coil, etc. In addition to the coil shape, a meander line shape may be used.
The input unit 120 and the output unit 220 can be configured using a loop coil, for example. Moreover, you may tap a track | line other than a loop.

An input terminal 122 and an output terminal 222 are provided at both ends of the coils of the input unit 120 and the output unit 220, respectively. To an input terminal 122 of the input unit 120, an electric circuit for supplying electric power P _i to the wireless power transmission apparatus 1 (not shown) are electrically connected. An electrical circuit (not shown) that receives power _Po extracted from the wireless power transmission device 1 is electrically connected to the output terminal 222 of the output unit 220.

The power transmission characteristics of the wireless power transmission device 1 that transmits power using the resonance phenomenon between the resonators can be obtained by calculating the transfer function of the circuit. Parameters required at that time, as shown in FIG. 2, the resonance frequency f _o and unloaded Q value Q _u of the resonator 102 and the resonator 202 of the present _embodiment, as well as the adjacent i-th resonator RF _i And an external Q value representing the coupling between the input unit 120 and the resonator RF ₁ connected to the input unit 120, and the coupling coefficient k _{i, i + 1} representing the rate of energy overlap integral between the (i + 1) th resonator RF _{i + 1.} Q _e-in is an external Q value Q _e-out representing the coupling between the output unit 220 and the resonator RF _{n + m} to which the output unit 220 is connected. Here, if the number n of the resonators 102 of the power transmitter 100 and the number m of the resonators 202 of the power receiver 200 are set, i is an integer from 1 to n + m.

Further, the resonance frequency f _o of each resonator 102 and the resonator 202, preferably takes approximately the same value. The reason is that if the resonance frequency of each resonator is different, the coupling becomes weak, and if the same coupling coefficient is taken, the transmission distance is shortened, and if the same distance is used, the transmission efficiency is lowered. Another reason is that if the resonance frequency is different, the design becomes complicated.
Unloaded Q value of each resonator RF _i is susceptible to different values for each resonator, and described in detail later, in this case, as shown in FIG. 2, all the Q _u.

Further, as shown in FIG. 1, the resonator 102 and the resonator 202 are ordered in the order of being adjacent from the input unit 120 side of the power transmitter 100 toward the output unit 220 of the power receiver 200. As described above, when the number of the resonators 102 of the power transmitter 100 is n and the number of the resonators 202 of the power receiver 200 is m, the resonators RF ₁ , resonators RF ₂ ,. . . , Resonators RF _n , resonators RF _{n + 1} ,. . . , Resonator RF _{n + m−1} and resonator RF _{n + m} . Here, i and j are integers having values between 1 and n + m, and if i ≠ j, k _{i, j} is the i-th resonator RF _i and j-th resonator RF _j from the input side. Gives the coupling coefficient between.

In addition, k _{i, j} = k _{j, i} because of the reciprocity of the passive circuit.
As shown in FIG. 2, in the wireless power transmission device 1 according to the embodiment of the present invention, each coupling coefficient k _{i, j} counted in order from the input unit 120 side of the resonator array 110 of the power transmitter 100 is The coupling coefficient k _{j, i} counted in order from the output unit 220 side of the resonator array 210 of the power receiver 200 takes substantially the same value between the coupling coefficients in the same order.
That is, in the resonator array 110 of the power transmitter 100 and the resonator array 210 of the power receiver 200, the coupling coefficient between adjacent resonators at symmetrical positions takes substantially the same value.

Furthermore, in the present invention, since the first resonator array 110 (FIG. 1) and the second resonator array 210 (FIG. 1) are each in series, in the calculation of the transfer function, between adjacent resonators Only the coupling coefficients k _{i, i + 1} (= k _{i + 1, i} ) are considered.

  Here, “resonator is adjacent” usually coincides with spatially adjacent. However, since the coupling coefficient is obtained based on the overlap integral of the energy stored in the magnetic field or electric field, it is affected by the spatial relative positional deviation and relative angular deviation between the resonators, or the surrounding electromagnetic environment. Does not necessarily match the size of the spatial distance.

Therefore, to be exact, when the coupling coefficient k _{i, j} (1 ≦ i <j ≦ n + m) is the maximum value of k _{i, j} , the resonator RF _i and the resonator RF _j are adjacent to each other. Let j = i + 1. When a specific distance between the resonators is taken, there is a maximum value for the coupling coefficient that can be realized at that distance. The reason is that the coupling coefficient can be obtained based on the overlap integral of the energy stored in the magnetic field or electric field, and the strength of the magnetic field or electric field formed by the resonator as the distance from the resonator increases in a uniform electromagnetic environment. Because it weakens. Alternatively, there is a maximum value for the distance between resonators that realizes a specific coupling coefficient. In the present invention, this inter-resonator distance is simply expressed as “inter-resonator distance”.

The wireless power transmission method of the present invention with the above configuration will be described below.
The wireless power transmission method of the present invention includes a first resonator including at least two resonators 102 (resonator RF ₁ and resonator RF _n ) having substantially the same resonance frequency in the wireless power transmission device 1 of FIG. The power transmitter 100 including the column 110 and the input unit 120 provided at one end of the first resonator column 110, and at least two resonators 202 (resonances) having substantially the same resonance frequency as the resonance frequency of the resonator 102 A second resonator array 210 including a resonator RF _{n + 1} and a resonator RF _{n + m} ), and an output unit 220 that extracts the power transmitted from the power transmitter 100 from one end of the second resonator array 210. 200, and the first resonator array 110 of the power transmitter 100 resonates through an electric field or a magnetic field generated by the resonator 102 to be connected in series, and the input unit 120 of the power transmitter 100 has a frequency of The resonance frequency Substantially the same to generate electric power P _i consisting of frequency components, the power P _i of the input unit 120 of the power transmitting device 100 is generated and supplied to one end of the first resonator column 110, a first resonance of the power transmitting device 100 and The resonator 102 (resonator RF _n ) at the other end 114 located at a different end from the one end 112 connected to the input unit 120 in the device array 110, and the output from the second resonator array 210 in the power receiver 200. The resonator 102 (resonator RF _{n + 1} ) at the other end 214 located at a different end from the one end 212 connected to the unit 220 is resonated through an electric field or a magnetic field to be coupled in series, and the output unit 220 of the power receiver 200 is the power _{P o,} which is transmitted from the power transmitting device 100, taken from one end 212 of the second resonator column 210.

FIG. 3 is a diagram for explaining the effect of the present invention and is a diagram illustrating the inter-resonator distance dependence of the coupling coefficient described in FIG. The horizontal axis represents the distance between resonators, and the vertical axis represents the coupling coefficient between resonators.
Except for the case where the strength of the coupling due to the electric field and the strength of the coupling due to the magnetic field are reversed, the coupling coefficient depends on the distance between the resonators as shown in FIG. The coupling coefficient of decreases monotonously.

Further, since the electric field and the magnetic field are spatially distributed and become 0 at infinity, as shown in FIG. 3, the inter-resonator distance dependency of the coupling coefficient is convex downward, and y = 0 when x = ∞. The curve becomes asymptotic to. Further, when the distance between resonators is small, the slope of the tangent l ₁ of the coupling coefficient curve is steep, if the distance between the resonators is large, the gradient of the tangent l ₂ of the coupling coefficient curve is gentle. Towards the △ _{x 1} tangents _{l 1} is wider than the △ _{x 2} tangents _{l 2} is narrow, towards the △ _{y 1} tangents _{l 1} it can be seen the width than the △ _{y 2} tangents _{l 2} is wide.
Note that it is conceivable that the coupling strength due to the electric field sharply decreases as the distance between the resonators increases as the coupling strength due to the magnetic field increases. Therefore, in order to further increase the distance between the resonators, it is desirable to use a resonance phenomenon caused by a magnetic field.

Further, in the present invention, “the coupling state of the resonators is in series” means that the coupling coefficient k _{i, j} (i + 1 <j, 1 ≦ i, j ≦ n + m) between the resonators that are not adjacent is an adjacent resonator. It means that it is sufficiently smaller than the intermediate coupling coefficient k _{i, i + 1} . Here, “sufficiently small” means that when the wireless power transmission device 1 is regarded as a bandpass filter, the inter-resonator coupling coefficient k _i is such that a sharp drop called a notch cannot be made in the passband of the frequency characteristics. _{, J} (i + 1 <j, 1 ≦ i, j ≦ n + m) is smaller than the coupling coefficient k _{i, i + 1} between adjacent resonators.

In the present invention, in order to eliminate instability with respect to temperature fluctuation or the like, it is desirable that there is no steep drop called a notch in the pass band of frequency characteristics when at least the wireless power transmission device 1 is regarded as a band pass filter. Alternatively, it is desirable that the transfer function represented by the Hurwitz polynomial does not have a zero so that such frequency characteristics can be obtained. This is because such a zero may occur when the inter-resonator coupling coefficient k _{i, j} (i + 1 <j, 1 ≦ i, j ≦ n + m) is not smaller than the adjacent resonator coupling coefficient k _{i, i + 1.} It is.

When there is no zero having a notch in the passband, at least in the passband, the all-pole band with the inter-resonator coupling coefficient ki _{, j} (i + 1 <j, 1≤i, j≤n + m) being 0 It is known from the design theory of a band pass filter that it can be analyzed approximately as a pass filter. Therefore, even in the present invention, the coupling coefficient k _{i, j} (i + 1 <j, 1 ≦ i, j ≦ n + m) between the resonators that are not adjacent to each other may be regarded as zero.

  Among all-pole bandpass filters, the Butterworth filter that provides the maximum flat characteristic ideally has zero reflection loss in the flat part of the passband. When this characteristic is used for the wireless power transmission apparatus 1 (FIG. 1), the power transmission efficiency can be maximized as compared with other filter characteristics. Here, the passband varies depending on the type of filter. In the case of a Butterworth filter, when the no-load Q value of the resonator is infinite, the transmission loss is 3 dB or less centering on the resonance frequency of the resonator. Refers to the frequency range.

  An example of the coupling coefficient of this Butterworth filter type wireless power transmission apparatus was calculated. The values are shown in Table 1. Table 1 shows the relationship between the number of resonators and the coupling coefficient of the Butterworth filter type wireless power transmission apparatus in the wireless power transmission apparatus according to the embodiment of the present invention when the relative bandwidth is 1%.

  The coupling coefficient shown in Table 1 is a value when the bandwidth is 1% of the center frequency (hereinafter, this condition is referred to as a relative bandwidth of 1%). Further, the coupling coefficient in Table 1 is a value just before the occurrence of a significant decrease in power transmission efficiency, which is almost close to a critical coupling state when a resonator having a Q value of about 1000 used in a wireless power transmission apparatus is used. It is. In addition, the example in Table 1 is an example of a condition that can maximize the distance between the resonators.

According to the present invention, as shown in FIG. 1 and FIG. 2, the total number n + m of the resonator 102 and the resonator 202 of the power transmitter 100 and the power receiver 200 is four or more, and the power transmitter 100 and the power receiver 200 The coupling coefficient between adjacent resonators is k _{i, i + 1} (2 ≦ i ≦ n + m−2).
Further, as shown in Table 1, k is obtained when the total number n + m of the power transmitter 100 and the resonator 102 and the resonator 202 of the power receiver 200 in FIG. 1 is 3 or less and when n + m is 4 or more. ₁ , ₂ and k _{n + m−1, n + m} , the coupling coefficient k _{i, i + 1} (2 ≦ i ≦ n + m−2) between adjacent resonators when n + m is 4 or more takes a value as small as 20%. There are many cases.

As described above, a small coupling coefficient indicates that the distance between the resonators can be increased. Like the wireless power transmission device 1 of the present embodiment, the resonators 102 and 102 of the power transmitter 100 and the power receiver 200 are By configuring the number n + m of the resonators 202 to be four or more, the distance between adjacent resonators in the wireless power transmission device 1 of FIG. 1, particularly the adjacent resonance between the power transmitter 100 and the power receiver 200. the vessel distance d ₁ can be long distance.

Also, as shown in FIG. 3, the inter-resonator distance dependence of the coupling coefficient is a curve that protrudes downward and asymptotically approaches y = 0 when x = ∞. Hit the part. Therefore, the variation of the coupling coefficient is small with respect to the variation of the inter-resonator distance, the characteristics of the pass band are not easily lost, and dip and the like are difficult to be performed. That is, according to the present invention, by reducing the coupling coefficient, it is possible to provide the wireless power transmission device 1 in which the variation in power transmission efficiency is small with respect to the variation in the distance d ₁ between adjacent resonators.

Further, according to the present invention, as shown in FIGS. 1 and 2, when both the number of resonators 102 of the power transmitter 100 and the number of resonators 202 of the power receiver 200 are equal, the power transmitter 100 and the power receiver 200 The total number n + m of the resonator 102 and the resonator 202 is an even number, and the coupling between adjacent resonators between the power transmitter 100 and the power receiver 200 corresponds to the middle of the even number of resonators. As shown in Table 1, in each row for each number of resonators, the minimum value of the coupling coefficient is the middle coupling coefficient. For example, in the case of 6 resonators, the middle coupling coefficient k _{3, 4} is the minimum value 0.005176. This is due to the fact that the two resonators located in the middle are farthest from the input unit 120 and the output unit 220 that are electromagnetically coupled through the external Q value.

Further, when the number of resonators is an even number, the coupling between the resonators is located in the middle of the wireless power transmission apparatus 1, and therefore the minimum value of the coupling coefficient is smaller than that in the case where the number of resonators is an odd number different by ± 1. For example, as shown in Table 1, the minimum value of the coupling coefficient when the number of resonators is an odd number of 5 is 0.005559, whereas the minimum value of the coupling coefficient when the number of resonators is an even number of 4 is , 0.005412, and the minimum value of the coupling coefficient in the case of the even number of resonators 6 is 0.005176.
Therefore, according to the present invention, by setting the number n + m of the resonator 102 of the power transmitter 100 and the resonator 202 of the power receiver 200 as an even number, the distance between adjacent resonators between the power transmitter 100 and the power receiver 200 is set. It is possible to provide the wireless power transmission device 1 that can increase the distance d ₁ (FIG. 1).

  Moreover, according to the wireless power transmission device 1 according to the embodiment of the present invention, the number of the resonators 102 of the power transmitter 100 and the number of the resonators 202 of the power receiver 200 are both equal, and the coupling coefficient is input from the middle. The unit 120 side and the output unit 220 side are arranged symmetrically. This is also shown in Table 1, and this is caused by the symmetry of the pole arrangement of the Hurwitz polynomial, which is the transfer function of the all-pole bandpass filter, and the reciprocity of the passive circuit, regardless of the type of filter.

By configuring the coupling coefficient in this way, not only Butterworth but also power transmission characteristics having various types of passband characteristics such as Chebyshev type can be obtained. Also, inadvertent dip in the passband can be avoided. While thus suppressing a decrease in power transmission efficiency or to eliminate a dip, providing wireless power transmission device 1 capable of long-distance adjacent resonators distance d ₁ between the power transmitting device 100 and the power receiver 200 can do.

As described above, according to the present invention, the distance between adjacent resonators in the wireless power transmission device 1, particularly the power transmitter 100, while suppressing the increase in size of the device and the decrease in power transmission efficiency. An excellent effect that the distance d ₁ between adjacent resonators between the power receivers 200 can be increased can be obtained. Furthermore, according to the present invention, it is possible to provide a wireless power transmission device with less variation in power transmission efficiency with respect to variation in the distance between adjacent resonators.

(Second Embodiment)
FIG. 7 is a block diagram schematically showing the wireless power transmission device 2 according to the embodiment of the present invention.
The wireless power transmission device 2 of the present embodiment differs from the above embodiment in the number of the resonators 302 in the first resonator array 310 of the power transmitter 300 and the resonators of the second resonator array 410 of the power receiver 400. The difference is that the number 402 is equal to two. The resonator 302 of the power transmitter 300 is the resonator RF ₁ and the resonator RF ₂ in order from the left in FIG. 7, and the resonator 402 of the power receiver 400 is the resonator RF ₃ and the resonator RF _{4 in} order from the left in FIG. Number it.

In the wireless power transmission device 2 according to the embodiment of the present invention, the number of the resonators 302 of the power transmitter 300 and the number of the resonators 402 of the power receiver 400 are both equal to two.
Hereinafter, an effect when the number of the resonators 302 of the power transmitter 300 and the number of the resonators 402 of the power receiver 400 of the wireless power transmission device 2 of the present embodiment are both equal to two will be described.

The minimum value of the coupling coefficient and the maximum value of the power transmission efficiency of the wireless power transmission device of Butterworth type with a relative bandwidth of 1% are calculated by using the number of resonators n + m as a variable. The value divided by the minimum value of the coupling coefficient is shown in FIG. Here, it is assumed that all the resonators have an unloaded Q value _Qu of 1000.

  FIG. 4 is a diagram showing calculation results for explaining the effect of the present invention, and shows the minimum value of the coupling coefficient of the wireless power transmission apparatus of Butterworth type having a relative bandwidth of 1% with the number of resonators n + m as a variable. The horizontal axis represents the number of resonators used in the wireless power transmission apparatus, and the vertical axis represents the minimum coupling coefficient among the coupling coefficients between a plurality of adjacent resonators.

  FIG. 5 is a diagram showing a calculation result for explaining the effect of the present invention, and shows the maximum value of the power transmission efficiency of the wireless power transmission apparatus of the Butterworth type with a bandwidth of 1% using the number of resonators n + m as a variable. . The horizontal axis represents the number of resonators used in the wireless power transmission apparatus, and the vertical axis represents the maximum value of the power transmission efficiency obtained at that time in the passband.

  FIG. 6 is a diagram showing calculation results for explaining the effect of the present invention. The horizontal axis represents the number of resonators used in the wireless power transmission device, and the vertical axis represents the value obtained by dividing the power transmission efficiency obtained by the number of resonators by the minimum value of the coupling coefficient.

Here, the power transmission efficiency should be high, and the coupling coefficient should be small in order to increase the distance between the resonators. Therefore, a value obtained by dividing the minimum value of the coupling coefficient of the power transmission efficiency, while suppressing a decrease in power transmission efficiency of the present invention, long distance adjacent resonators distance d ₂ between the power transmitting device 300 and the power reception unit 400 It becomes one index for becoming.

Here, the minimum value of the coupling coefficient is the minimum value of the coupling coefficient k _{i, i + 1} (1 ≦ i ≦ n + m−1) between adjacent resonators when the number of resonators n + m is fixed. The minimum value of the coupling coefficient is shown, and corresponds to the coupling coefficient used between adjacent resonators between the power transmitter 300 and the power receiver 400 in the present invention. According to FIG. 4, when the number of resonators is four, the coupling coefficient rapidly decreases by about 20% compared to the case of three resonators.

On the other hand, according to FIG. 5, the power transmission efficiency decreases gently and smoothly as the number of resonators increases. Therefore, by the resonator number 4, while suppressing a decrease in power transmission efficiency and a long distance the adjacent resonators distance d ₂ between the power transmitting device 300 and the power receiver 400. Further, when the number of resonators is 4, the value obtained by dividing the power transmission efficiency by the minimum value of the coupling coefficient also takes the maximum value. Therefore, according to the present invention, it is possible to provide a wireless power transmission device that can increase the distance d ₂ between adjacent resonators between the power transmitter 300 and the power receiver 400 while suppressing a decrease in power transmission efficiency. .

In addition, the wireless power transmission device 2 according to the embodiment of the present invention includes the resonator RF at the other end that is located at an end different from the one connected to the input unit 320 in the first resonator array 310 of the power transmitter 300. ₂ , the resonator having the maximum unloaded Q value is used. The second resonator array 410 of the power receiver 400 has no resonance at the other end of the resonator RF ₃ located at a different end from the one connected to the output unit 420. A resonator having a maximum load Q value can be used.

Note that the above-described configuration can also be adopted in the embodiment shown in FIG. For example, the wireless power transmission device 1 according to the embodiment of the present invention shown in FIG. 1 includes the other end of the first resonator array 110 of the power transmitter 100 that is located at a different end from the one connected to the input unit 120. A resonator having a maximum unloaded Q value is used as the resonator RF _n or the other end of the second resonator array 210 of the power receiver 200 is located at a different end from the one connected to the output unit 220. A resonator having a maximum unloaded Q value can be used as the resonator RF _{n + 1} .

Further, a resonator having a high unloaded Q value tends to be enlarged. Therefore, in order to suppress the increase in size, it is necessary to consider the optimum distribution of the no-load Q value in the limited resonator having the no-load Q value.
In the wireless power transmission device 2 of the present embodiment in FIG. 7, when the number of the resonators 302 of the power transmitter 300 and the number of the resonators 402 of the power receiver 400 are both equal, the unloaded Q value of the resonator The maximum power transmission efficiency within the frequency band depending on the combination is shown in FIG. Incidentally, calculated in fractional bandwidth of 1% Butterworth, a combination of four of the unloaded Q value _{Q U} of the resonator at 1000 or 100, it was divided case of (a) from (j).

In this case classification, the case where the power transmission efficiency is the same in consideration of the reciprocity of the passive circuit was previously removed. For _{example, (Q U1, Q U2,} Q U3, Q U4) = (100,1000,1000,1000) of the case of _{(b) (Q U1, Q} U2, Q U3, Q U4) = (1000,1000 , 1000, 100), the power transmission efficiency is not shown in FIG.

If the Q value of all the resonators can be increased as shown in (a), the maximum efficiency can be obtained, but in this case, the apparatus is increased in size.
Therefore, for example, in the case of (b) and (c) which suppresses enlargement by using one resonator having a small Q value, and in the case of (d) to (g) where two are used, three are used (h ) And (i) are assumed. In comparison, when a resonator having a high unloaded Q value is arranged in the second and third resonators among the four resonators, resonances having a high unloaded Q value are arranged in the first and fourth resonators. It can be seen that the power transmission efficiency is higher compared to the case where the device is arranged.

Therefore, according to the present invention, the number of the resonators 302 of the power transmitter 300 is equal to the number of the resonators 402 of the power receiver 400, and the other end is located at a different end from the one connected to the input unit 320. resonator RF _2, or, when the unloaded Q value in the resonator RF ₄ of the other end located at one end different from an end portion connected to the output unit 220 using the maximum of the resonator to suppress an increase in size of the apparatus At the same time, it is possible to provide the wireless power transmission device 1 that can increase the distance d ₂ (FIG. 7) between the adjacent resonators between the power transmitter 300 and the power receiver 400 while suppressing a decrease in power transmission efficiency. Furthermore, according to the present invention, it is possible to provide a wireless power transmission device with less variation in power transmission efficiency with respect to variation in the distance between adjacent resonators.

  As described above, according to the present invention, it is possible to provide a wireless power transmission device that exhibits the same effects as those of the above embodiment.

As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.
For example, it is desirable to arrange resonators with high unloaded Q values in ascending order of coupling coefficient between adjacent resonators. Furthermore, it is desirable to distribute the unloaded Q value of the adjacent resonators in proportion to the reciprocal of the coupling coefficient between adjacent resonators.

An embodiment of the wireless power transmission apparatus of the present invention will be described below with reference to FIG.
First, the power P _i input from the left in FIG. 7 passes through the input unit 320 and impedance-matches through the external Q value Q _e-in to resonate the resonator RF ₁ . The resonator RF ₁ and the resonator RF ₂ are resonated through a magnetic field, and the coupling coefficient is k ₁ and ₂ . The magnetic field formed by the resonator RF ₂ resonates the resonator RF ₃ through the coupling coefficient k ₂ , ₃ , and the resonator RF ₃ resonates. Further, the magnetic field formed by the resonator RF ₃ causes the resonator RF ₄ to resonate through the coupling coefficient k ₃ , ₄ , and the resonator RF ₄ resonates.

Finally, electric power _Po is transmitted to the output unit through the external Q value Q _e-out between the resonator RF ₄ and the output unit 420. At this time, gap coupling or tap coupling may be used for electromagnetic coupling between the input unit 320 and the resonator RF ₁ , or between the resonator RF ₄ and the output unit 420. Can be consistent. As the resonator RF ₁ and the resonator RF ₄ , for example, a resonator having a Q value slightly smaller than that of the other resonators RF ₂ and RF ₃ may be used in order to reduce the size.

On the other hand, as described above, it is desirable that the resonator RF ₂ and the resonator RF ₃ use a resonator having a high unloaded Q value as much as possible in order to make the distance d ₂ between them as long as possible. In order to realize a desired coupling coefficient, the relative position dependence and relative angle dependence of the coupling coefficient between the resonators are measured in advance. At this time, in order to reduce the size of the power transmitting device 300 and the power receiver 400, it can be considered, such as intentionally shifting the angle of the resonator RF ₁ and the resonator RF _2, for miniaturization of these ideas bandpass filter Has been studied for a long time, and the idea can be diverted. The external Q value Q _e-in and Q _e-out are also measured _in advance between the input unit 320 and the resonator RF ₁ or between the resonator RF ₄ and the output unit 420 in order to obtain a desired value. A value can be obtained.

  On the other hand, the desired coupling coefficient can be calculated by mode coupling theory by determining the corresponding filter type from the unloaded Q value of the resonator used in advance and the required bandwidth. Further, it is preferable to confirm that desired characteristics can be obtained by calculating a transfer function. The center frequency and bandwidth of the resonator can be determined from the frequency used for power transmission.

For example, a frequency of 13.56 MHz which is an ISM band (Industry Science Medical band) can be selected as the center frequency of the resonator 302 and the resonator 402, that is, the resonance frequency. At this time, the higher the accuracy of the center frequency of the resonator 302 and the resonator 402 is, the better. However, there is no significant difference as long as they are arranged in units of 1 kHz, which is sufficiently smaller than 1 / Q _u of the resonance frequency. In the present specification, a situation that does not have such a large difference is referred to as “substantially the same”.

In this embodiment, the unloaded Q value of the resonator RF ₁ and the resonator RF ₄ is 785, and the unloaded Q value of the resonator RF ₂ and the resonator RF ₃ is 1215. In addition, k _1,2 = k _3,4 = 0.008031, and k _2,3 = 0.005169 are selected as the coupling coefficients. In this case, the no-load Q value of the resonator is uniformly set to 1000, and the specific band is 1% (in Table 1, k _1,2 = k _3,4 = 0.008409, k _2,3 = 0.005412). the same power transmission efficiency and the power transmission efficiency 59.46% (Fig. 8) in the case of a) is obtained in a smaller value of _{k 2,3} (.005169). That is, while suppressing a decrease in power transmission efficiency and a long distance the adjacent resonators distance d ₂ between the power transmitting device 300 and the power receiver 400.

In order to make the coupling coefficients k _{1, 2} and k ₃ , ₄ equal, the distance between the resonators, the relative angle between the resonators, the positional deviation between the resonators are adjusted, or the dielectric, magnetic material, Alternatively, it can be realized by inserting a metal.

  FIG. 9 is a diagram showing a calculation result for explaining the effect of the present invention. The horizontal axis shows the combination of the no-load Q values of the four resonators when the sum of the no-load Q values is set to 4000. The vertical axis represents the maximum value of the power transmission efficiency obtained at that time in the passband.

As shown in FIG. 9, the unloaded Q value of the resonator RF ₁ or the resonator RF ₄ is set under the condition that k _1,2 = k _3,4 = 0.008031, k _2,3 = 0.005169, and When the sum of the resonator RF ₂ or the resonator RF _{3 and} the no-load Q value is constant 2000, the change in the power transmission efficiency due to the combination of the no-load Q values is shown. As shown in this figure, when the unloaded Q value of the resonator RF ₁ or the resonator RF ₄ is 785 and the unloaded Q value of the resonator RF ₂ or the resonator RF ₃ is 1215, the maximum power transfer efficiency 59.46 is obtained. % Is obtained. This value is obtained by setting the unloaded Q value of the resonator RF ₁ or the resonator RF _{4 and} the unloaded Q value of the resonator RF ₂ or the resonator RF ₃ to be a constant 2000, and the coupling coefficient between adjacent resonators. It is a value distributed at a ratio of 1 / k _{1,2 of the} reciprocal and 1 / k _2,3 .
As described above, it is desirable to arrange resonators having a high unloaded Q value in ascending order of coupling coefficient between adjacent resonators. Furthermore, it is desirable to distribute the unloaded Q value of adjacent resonators in proportion to the inverse of the coupling coefficient between adjacent resonators.

As a comparative example, when using the coupling coefficient and the inter-resonator distance dependency when the inter-line distance g = 2 cm of the spiral coil resonator shown in FIG. When the number of resonators n + m is 2, k _1,2 = 0.0106, and the distance between the resonators is 52 cm.
On the other hand, when the number of resonators n + m is 4 according to the present invention with a specific bandwidth of 1.5%, k _2,3 = 0.00812, and the distance between resonators is 58.35 cm. Thus, the distance between adjacent resonators can be increased by 12%.

  The reason why the specific bandwidth is 1.5% is determined by the data range shown in FIG. In the above calculation, the distance is increased by 12%. However, if the shape of the resonator is devised as shown in FIG. 16 of Non-Patent Document 2, and the inter-resonator distance dependency of the coupling coefficient having a gentler slope is realized, Needless to say, the effect of increasing the distance is increased.

  In the embodiment of the present invention, the case of resonance by a magnetic field has been described, but it goes without saying that when the resonator is a dielectric resonator, resonance is caused by an electric field and the present invention is applied.

As described above, according to the present invention, the distance between adjacent resonators in the wireless power transmission device 1, particularly the power transmitter 100, can be reduced while suppressing the increase in size of the device and the decrease in power transmission efficiency. The distance d ₁ between adjacent resonators between the electric devices 200 can be increased, and a wireless power transmission device with less variation in power transmission efficiency with respect to variation in the distance between adjacent resonators can be provided. .

  Note that, as a wireless power transmission device in which the variation in power transmission efficiency is small with respect to the variation in the distance between adjacent resonators, the number of resonators n + m may be an odd number. In this case, the maximum value of the transmission efficiency can always be obtained at the resonance frequency or the center frequency in terms of frequency characteristics. Therefore, when power is transmitted at the resonance frequency, even if the distance between adjacent resonators varies, power transmission can always be performed with the maximum value of the transmission efficiency, and thus a wireless power transmission device with less variation in power transmission efficiency is provided. be able to. However, other effects such as long distance cannot be obtained.

  While the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

1 wireless power transmission apparatus 100 power transmitting device _{102, RF 1, ···, RF} n resonators 110 first resonator column 112 one end 114 other end 120 input unit 122 input terminal 200 receiving unit _{202, RF n} + _1, ··· , _{RF n + m} resonator 210 between the second resonator column 212 one end 214 other end 220 output section 222 output terminal _{d 1} adjacent resonator length _{f o} resonance frequency _{Q u} unloaded Q value k coupling coefficient _{Q e-in, Q e -out} external Q value 2 wireless power transmission unit 300 transmitting unit _302, RF 1, RF ₂ resonator 310 first resonator column 320 input unit 400 receiving unit _402, RF _3, RF ₄ resonator 410 second resonator Column 420 Output unit d ₂ Distance between adjacent resonators

Claims (6)

A power transmitter, and a power receiver that extracts power transmitted from the power transmitter,
The power transmitter
A first resonator array in which at least two resonators having substantially the same resonance frequency resonate through an electric field or a magnetic field generated by the resonator and are coupled in series;
An input unit that generates power having a frequency component whose frequency is substantially the same as the resonance frequency, and supplies the generated power to one end of the first resonator array;
The power receiver
A second resonator array in which at least two resonators having substantially the same resonance frequency as the resonance frequency resonate through an electric field or a magnetic field generated by the resonator and are coupled in series;
An output unit that extracts the power transmitted from the power transmitter from one end of the second resonator array;
Of the first resonator row of the power transmitter, the resonator at the other end located at a different end from the one end connected to the input unit, and the second resonator row of the power receiver, A wireless power transmission device in which a resonator at the other end located at a different end from the one end connected to the output unit is resonated through an electric field or a magnetic field to form a coupled state in series. The wireless power transmission device according to claim 1,
The wireless power transmission apparatus in which the number of the resonators of the power transmitter and the number of the resonators of the power receiver are both equal. The wireless power transmission device according to claim 2,
Each coupling coefficient of the first resonator row of the power transmitter, counted in order from the input unit side,
Coupling coefficients of the second resonator array of the power receiver counted from the output unit side in order,
A wireless power transmission apparatus that takes substantially the same value between coupling coefficients in the same order. The wireless power transmission device according to claim 3,
The wireless power transmission apparatus in which the number of the resonators of the power transmitter and the number of the resonators of the power receiver are both equal to two. The wireless power transmission device according to claim 1,
A resonator having a maximum no-load Q value is used as a resonator located at the end different from the one end connected to the input unit in the first resonator row of the power transmitter, or the power receiver A wireless power transmission device using a resonator having a maximum unloaded Q value as a resonator located at the end portion different from the one end connected to the output portion in the second resonator row. A power transmitter including a first resonator array including at least two resonators having substantially the same resonance frequency, and an input provided at one end of the first resonator array; and the resonance frequency and the resonance frequency. A power receiver including: a second resonator array including at least two resonators substantially identical to each other; and an output unit that extracts power transmitted from the power transmitter from one end of the second resonator array; Provided,
The first resonator array of the power transmitter is resonated through an electric field or a magnetic field generated by the resonator to be in a series coupled state,
The input unit of the power transmitter generates power having a frequency component whose frequency is substantially the same as the resonance frequency,
The input of the power transmitter supplies the generated power to one end of the first array of resonators;
Of the first resonator row of the power transmitter, the resonator at the other end located at a different end from the one end connected to the input unit, and the second resonator row of the power receiver, Resonating through the electric field or magnetic field with the resonator at the other end located at a different end from the one end connected to the output unit, in a series coupled state,
The wireless power transmission method, wherein the output unit of the power receiver extracts the power transmitted from the power transmitter from the one end of the second resonator array.

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