JP2013078166A - Non-contact power transmission apparatus and non-contact power transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power transmission apparatus which can transmit power selectively to a specific power reception apparatus by a simple configuration.SOLUTION: The non-contact power transmission apparatus comprises a transmission device 1 having a transmission resonator consisting of a resonance coil 4a for transmission and a resonance capacitor, and a reception device 2 having a reception resonator consisting of a resonance coil 4b for reception and a resonance capacitor. A transmission auxiliary device 9 having an auxiliary resonator of variable resonance frequency f3 consisting of an auxiliary coil 10 and a resonance capacitor 11 is also provided, and disposed to face the transmission device. Between the resonance coil for transmission and the auxiliary coil, a space for disposing the resonance coil for reception can be formed, and the resonance frequency ft of a transmission side resonance system configured of the transmission resonator and the auxiliary resonator can be adjusted by adjusting the resonance frequency f3.

Description

  The present invention relates to a non-contact power transmission apparatus that performs non-contact (wireless) power transmission between a power transmission coil and a power reception coil via magnetic field resonance.

  As a method of transmitting power in a non-contact manner, an electromagnetic induction type by electromagnetic induction (several hundreds of kHz), an electric field / magnetic field resonance type by transmission between LC resonances via electric field or magnetic field resonance, a microwave power transmission type by radio waves (several GHz), Alternatively, a laser power transmission type using electromagnetic waves (light) in the visible light region is known. Among them, the electromagnetic induction type has already been put into practical use. This has the advantage that it can be realized with a simple circuit (transformer system), but there is also a problem that the transmission distance is short.

  Therefore, recently, electric field / magnetic field resonance type power transmission capable of short-distance transmission (up to 2 m) has attracted attention. Among these, in the case of the electric field resonance type, when a hand or the like is put in the transmission path, the human body is a dielectric, so that energy is absorbed as heat and dielectric loss occurs. On the other hand, in the case of the magnetic resonance type, the human body hardly absorbs energy, and dielectric loss can be avoided. From this point of view, attention to the magnetic resonance type has been increasing.

  FIG. 7 is a front view showing an outline of a configuration example of a conventional power transmission device using magnetic field resonance. The power transmission device 1 includes a power transmission coil that combines the loop coil 3a and the power transmission resonance coil 4a, and the power reception device 2 includes a power reception coil that combines the loop coil 3b and the power reception resonance coil 4b. A high frequency power driver 5 is connected to the loop coil 3a of the power transmission device 1, and the power of the AC power source (AC 100V) 6 is converted into high frequency power that can be transmitted and supplied. For example, a rechargeable battery 8 is connected to the loop coil 3 b of the power receiving device 2 as a load via a rectifier 7.

The loop coil 3a is a dielectric element that is excited by an electric signal supplied from the high-frequency power driver 5 and transmits the electric signal to the power transmission resonance coil 4a by electromagnetic induction. The power transmission resonance coil 4a generates a magnetic field based on the electrical signal output from the loop coil 3a. The power transmission resonance coil 4a has a maximum magnetic field strength at a resonance frequency f0 = 1 / {2π (LC) ^1/2 } (L is an inductance of the power transmission resonance coil 4a, and C is a stray capacitance). It becomes. The electric power supplied to the power transmission resonance coil 4a is transmitted in a non-contact manner to the power reception resonance coil 4b by magnetic field resonance. The transmitted power is transmitted from the power receiving resonance coil 4 b to the loop coil 3 b by electromagnetic induction, rectified by the rectifier 7 and supplied to the rechargeable battery 8. In this case, the resonance frequencies of the power transmission resonance coil 4a and the power reception device 2 are set to be the same.

  In such a magnetic resonance type non-contact power transmission, Patent Document 1 discloses a method of providing a plurality of power receiving devices for one power transmitting device and selectively charging a specific power receiving device from the plurality of power receiving devices. Yes. That is, the power transmission device has a mechanism that varies the resonance frequency, each of the plurality of power reception devices has a specific resonance frequency, and by changing the resonance frequency of the power transmission device, each power reception device has a different specific resonance frequency. In contrast, power can be selectively transmitted.

JP 2010-63245 A

  In the technique disclosed in Patent Document 1, as a variable mechanism for adjusting the resonance frequency of the power transmission device to the specific resonance frequency of each power reception device, for example, the wire length of the coil is switched by opening and closing of the relay to switch the resonance coil. A structure with variable inductance is used. Alternatively, as a mechanism for changing the resonance frequency of the power transmission device, a structure in which the entire length of the resonance coil is physically switched by an actuator is used.

  Further, as another conventional technique, by selectively switching the oscillation frequency of the AC power source of the power transmission device to the resonance frequency of the power receiving device of the power receiving destination, the power is selectively transmitted to the power receiving devices having different inherent resonance frequencies. Has also been considered.

  However, in such a conventional method for changing the resonance frequency of the power transmission device, there are problems that the structure and control of the device are complicated and it is difficult to reduce the size of the power transmission device.

  The present invention solves such problems in the prior art, and provides a non-contact power transmission apparatus and a non-contact power transmission method capable of selectively transmitting power to a specific power receiving apparatus with a simple configuration. The purpose is to provide.

  The non-contact power transmission device of the present invention has, as a basic configuration, a power transmission device having a power transmission resonator constituted by a power transmission resonance coil and a resonance capacitor, and a power reception resonator constituted by a power reception resonance coil and a resonance capacitance. A power reception device, and transmits power from the power transmission device to the power reception device via magnetic field resonance between the power transmission resonance coil and the power reception resonance coil.

  In order to solve the above-described problem, the non-contact power transmission apparatus of the present invention further includes a power transmission auxiliary device that includes an auxiliary coil and a resonance capacitor, and includes an auxiliary resonator whose resonance frequency f3 is variable. Is disposed opposite to the power transmission device, and a power reception space in which the power reception resonance coil is disposed can be formed between the power transmission resonance coil and the auxiliary coil, and the resonance frequency f3 is adjusted. Thus, the resonance frequency ft of the power transmission side resonance system formed by the power transmission resonator and the auxiliary resonator can be adjusted.

  A non-contact power transmission method of the present invention includes a power transmission device having a power transmission resonator configured by a power transmission resonance coil and a resonance capacitor, and a power reception device having a power reception resonator configured by a power reception resonance coil and a resonance capacitance. A method of transmitting power from the power transmission device to the power reception device via magnetic field resonance between the power transmission resonance coil and the power reception resonance coil, the method including an auxiliary coil and a resonance capacitor, and a resonance frequency f3 And further using a power transmission auxiliary device having an auxiliary resonator, wherein the power transmission auxiliary device is disposed opposite to the power transmission device, and a power receiving space formed between the power transmission resonance coil and the auxiliary coil is provided. By arranging the power receiving resonance coil and adjusting the resonance frequency f3, the resonance frequency ft of the power transmission side resonance system constituted by the power transmission resonator and the auxiliary resonator is set. And integer and performing power transmission.

  According to the present invention, a power transmission auxiliary device is provided in addition to the power transmission device and the power reception device, and the power reception device is arranged in the power reception space between the power transmission device and the power transmission auxiliary device, thereby increasing the resonance frequency of the power transmission side resonance system. It can be adjusted by the device, and non-contact power transmission can be selectively performed with respect to a specific power receiving device having a specific resonance frequency among the plurality of power receiving devices.

  Further, the distance dependency with which the power transmission efficiency is substantially flat can be obtained regardless of the position of the power receiving resonance coil of the power receiving device. Furthermore, the power transmission possible distance can be significantly increased compared to the case where there is no power transmission auxiliary device.

Schematic cross-sectional view showing the configuration of the non-contact power transmission apparatus in the first embodiment Schematic sectional view showing the arrangement of each element device at the time of measurement by a VNA (vector network analyzer) for the power transmission side resonance system of the non-contact power transmission device The graph which shows transition of the resonant frequency ft with respect to the resonant frequency f3 of an auxiliary resonator about the power transmission side resonant system of the non-contact power transmission device Waveform diagram showing VNA measurement output at each of the three values of the resonance frequency f3 of the auxiliary resonator for the power transmission side resonance system of the non-contact power transmission apparatus Schematic sectional view showing the arrangement of each element device at the time of VNA measurement for the non-contact power transmission device Graph showing the dependence of power transmission efficiency on the resonance frequency f3 of the auxiliary resonator for the non-contact power transmission device Schematic sectional view showing the arrangement of each element device at the time of VNA measurement in which the resonance frequency f1 of the power transmission resonator is changed with respect to the non-contact power transmission device About the non-contact power transmission device, a graph showing the dependence of the power transmission efficiency on the resonance frequency f1 of the power transmission resonator Schematic cross-sectional view showing the configuration of the non-contact power transmission apparatus in the second embodiment Plan view of the contactless power transmission device About the non-contact power transmission device, a graph showing the dependence of the power transmission efficiency to one power receiving device on the resonance frequency f1 of the power transmission resonator in the arrangement of FIG. 5A About the non-contact power transmission device, a graph showing the dependency of the power transmission efficiency to the other power receiving device in the arrangement of FIG. 5A on the resonance frequency f1 of the power transmission resonator Schematic cross-sectional view showing the configuration of the non-contact power transmission apparatus in the third embodiment Sectional drawing which shows the structure of the non-contact electric power transmission apparatus in a prior art

  The non-contact power transmission apparatus of the present invention can take the following aspects based on the above configuration.

  That is, the resonance capacitance of the power transmission auxiliary device is configured by a variable capacitor, and the resonance frequency f3 of the auxiliary resonator can be adjusted by adjusting the variable capacitor.

  The resonance capacity of the power transmission auxiliary device is composed of a plurality of fixed capacitors each having a different capacitance value, and the resonance frequency of the auxiliary resonator is switched by switching the fixed capacitor selectively connected to the auxiliary coil. It can be set as the structure which can adjust f3.

  Moreover, it is preferable that the diameter d1 of the power transmission resonance coil, the diameter d2 of the power reception resonance coil, and the diameter d3 of the auxiliary coil satisfy the relationship of d1> d2 and d2 <d3. If this relationship is maintained, effects such as an increase in the power transferable distance can be obtained. In particular, it is preferable to satisfy the relationship of d1 = d3 and d1> d2. Thereby, a great effect can be obtained in terms of improvement of transmission efficiency characteristics (such as expansion of the power receiving range). Of course, the same effect can be obtained not only in the case of a circular coil but also in a form in which a rectangular coil or the like is arranged.

  Moreover, it is preferable that the central axis of the power transmission resonance coil, the central axis of the auxiliary coil, and the central axis of the power reception resonance coil are on the same axis.

  Further, one power receiving device is arranged for one power transmitting device, and the resonance frequency f3 can be set under the condition of f1 ≠ f3. In this case, it is preferable that the resonance frequency f3 is set under the condition of f1 <f3.

  Further, a plurality of power receiving devices are arranged for one power transmitting device, and the resonance frequencies f2 of the power receiving resonators of the plurality of power receiving devices are all different and f2 ≠ f3. it can.

  Further, a plurality of power receiving devices are arranged for one power transmitting device, and at least some of the power receiving resonators of the plurality of power receiving devices have different resonance frequencies f2 and f1 ≠ f2. It can be configured.

  In addition, the power transmission device and the power transmission auxiliary device are held, a housing capable of setting the mutual positional relationship between the power transmission device and the power transmission auxiliary device so that the power receiving space is formed, The power receiving device can be detachably attached to the power receiving space, and at least the periphery of the power transmission resonance coil, the auxiliary coil, and the power reception resonance coil are electromagnetically shielded in the housing It can be set as the structure which performs electric power transmission.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1>
1 is a cross-sectional view illustrating a configuration of a magnetic field resonance type non-contact power transmission apparatus according to Embodiment 1. FIG. In addition, about the element similar to the non-contact electric power transmission apparatus of the prior art example shown in FIG. 7, the same reference number is attached | subjected and the repetition of description is simplified. Here, a case where there is one power transmission device 1 and one power reception device 2 will be described.

  This non-contact power transmission device is configured by adding a power transmission auxiliary device 9 to the conventional power transmission device 1 and power reception device 2, and the power reception device 2 is arranged in a power receiving space between the power transmission device 1 and the power transmission auxiliary device 9. Non-contact power transmission is performed in the state. The power transmission device 1 converts the power of the AC power supply (AC 100 V) into high-frequency power that can be transmitted and transmits the power, and the power receiving device 2 receives the power. The power transmission auxiliary device 9 has a function of adjusting the resonance frequency of the resonance system related to the power transmission device 1 during power transmission to an appropriate relationship with the resonance frequency of the resonance system of the power receiving device 2.

  The power transmission device 1 includes a high-frequency power driver 5 that converts power from an AC power source (AC 100 V) 6 into high-frequency power that can be transmitted, a loop coil 3a for power transmission, and a resonance coil 4a for power transmission. Depending on the case, the loop coil 3a for power transmission may not be provided. In other words, it is possible to supply power with another known configuration. Although illustration is omitted, a resonance capacitor is connected to the power transmission resonance coil 4a to constitute a power transmission resonator. As the resonant capacitance, a variable capacitor or a fixed capacitor may be connected as a circuit element, or a configuration using a stray capacitance may be used. In the following description, the resonance frequency f1 of the power transmission resonator alone is described as “resonance frequency f1 of the power transmission device 1” so that the relationship with the figure can be easily understood.

  The power transmission auxiliary device 9 includes an auxiliary coil (air core coil or the like) 10 and an adjustment capacitor 11, and an auxiliary resonator is configured by both elements. The adjustment capacitor 11 is composed of a variable capacitor having a variable capacitance value, and is referred to as an adjustment variable capacitor 11 in the following description. However, as the adjustment capacitor 11, a plurality of fixed capacitors having different capacitance values are used in place of the variable capacitors, and one of the fixed capacitors is selectively connected to the auxiliary coil 10 to change the capacitance value. It can also be set as the structure to do. In the following description, the resonance frequency f3 of the auxiliary resonator alone is described as “resonance frequency f3 of the power transmission auxiliary device 9” so that the relationship with the drawing can be easily understood.

  Although not shown in the figure, means for monitoring the reflected power, resonance frequency, flowing current, voltage, etc. of the resonance coil for power transmission 4a as necessary, the power transmission device 1, the power reception device 2, and the power transmission auxiliary device 9 A circuit for exchanging information between each other can be included. When such a configuration is adopted, the capacitance value of the variable capacitor 11 for adjustment can be automatically controlled.

  In the power receiving device 2, a power receiving resonance coil 4 b and a loop coil 3 b are combined as a power receiving coil. The electric power obtained by the loop coil 3 b is stored in the rechargeable battery 8 via at least the rectifier circuit 7. Although illustration is omitted, a resonance capacitor is connected to the power reception resonance coil 4b to constitute a power reception resonator. As the resonant capacitance, a variable capacitor or a fixed capacitor may be connected as a circuit element, or a configuration using a stray capacitance may be used. In the following description, the resonance frequency f2 of the power receiving resonator alone is described as “the resonance frequency f2 of the power receiving device 2” so that the relationship with the drawing can be easily understood.

  When a small battery (such as a coin battery) is used as the rechargeable battery 8, it is preferable to overlap the loop coil 3b and the rechargeable battery 8 to reduce the installation area (for example, a coil-on battery). In this case, magnetic flux leaks from the loop coil 3b to the rechargeable battery 8 to generate an eddy current and a loss (eddy current loss) occurs between the loop coil 3b and the rechargeable battery 8 at a resonance frequency during transmission. It is desirable to arrange a radio wave absorber having magnetic susceptibility. Further, in order to reduce the total thickness, the loop coil 3b and the rechargeable battery 8 may be brought into close contact with each other with a radio wave absorber interposed therebetween.

  As described above, by arranging the power transmission auxiliary device 9 and the power transmission device 1 to face each other, a power reception space is formed between the power transmission resonance coil 4a and the auxiliary coil 10, and the power reception device 2 receives power in the power reception space. The resonance coil 4b for use is arranged.

  In the present embodiment, the loop coil 3a and the power transmission resonance coil 4a in the power transmission device 1 have the same functions as those shown in FIG. 7, but in order to reduce the thickness, for example, a Cu coil having a diameter of about 1 mm ( A planar coil in which a litz wire and a coating are spirally wound on the same plane is used (diameter is 70 mmΦ). Further, the loop coil 3b and the power receiving resonance coil 4b in the power receiving device 2 have the same functions as those shown in FIG. A Cu foil having a thickness of about 70 μm is formed of a thin film coil formed in a spiral shape on the same plane (diameter is 20 mmΦ). Thus, by increasing the diameter of the coil on the power transmission side and decreasing the diameter on the power reception side, it is possible to extend the power transmission possible distance. In order to reduce the thickness of the substrate, the power receiving loop coil 3b and the power receiving resonance coil 4b may be separately formed on both surfaces of the substrate.

  The function of the power transmission auxiliary device 9 that is a feature of the contactless power transmission device of the present embodiment will be described in more detail. According to the above configuration, a resonance system including the power transmission resonator including the power transmission resonance coil 4a and the auxiliary resonator including the auxiliary coil 10 is configured by the coupling of the power transmission resonance coil 4a and the auxiliary coil 10, and in the following description, This is referred to as a power transmission side resonance system. The resonance frequency of the power transmission side resonance system is described as ft.

  According to the configuration of the present embodiment, the distance over which power can be transmitted is increased compared to the case where there is no power transmission auxiliary device 9. This is presumably because the reach distance of the magnetic flux from the power transmission resonance coil 4a is increased by disposing the auxiliary coil 10 opposite to the power transmission resonance coil 4a. Accordingly, the power receiving resonance coil 4b is not properly disposed with respect to the power transmission resonance coil 4a, for example, the surface suitable for power reception of the power reception device 2 is not properly opposed to the power transmission device 1. However, efficient power transmission is possible without providing an adjustment circuit in the power receiving device 2.

  On the other hand, in the configuration shown in FIG. 1, when the distance between the power transmission resonance coil 4a and the auxiliary coil 10 is short, the coupling state between the two becomes strong (tight coupling state), and the power transmission resonator and the auxiliary resonance The resonant frequency of the power transmission side resonance system by the power supply is divided into two (bimodal characteristics). That is, by making the power transmission auxiliary device 9 face each other, two peaks appear and move on both sides of the inherent resonance frequency of the power transmission resonance coil 4a. On the other hand, the resonance frequency ft of the power transmission side resonance system is received by adjusting the capacitance value C of the adjustment variable capacitor 11 connected to the auxiliary coil 10 and appropriately setting the resonance frequency f3 of the power transmission auxiliary device 9. The resonance frequency f2 of the device 2 can be matched. Thereby, the power transmission efficiency from the power transmission resonance coil 4a can be maintained at a practically sufficient level, and characteristics such as a power transmission distance can be improved.

  The adjustment of the capacitance value C of the variable capacitor 11 for adjustment is desirably performed so that the resonance frequency ft coincides with the resonance frequency f2, but a corresponding effect can be obtained even if it does not coincide completely. In other words, the resonance frequency f3 of the power transmission auxiliary device 9 is adjusted so that the peak of the resonance frequency ft of the power transmission side resonance system is sufficiently close to the resonance frequency f2 of the power receiving device 2 as compared with the resonance frequency f1 of the power transmission device 1. That's fine. That is, to make the resonance frequency ft coincide with f2 is that the resonance frequency ft is close to f2 to the extent that power transmission efficiency practically equivalent to that when the resonance frequency ft coincides with f2. Used to mean including.

  In order to sufficiently obtain the effect of such adjustment, the auxiliary coil 10 constituting the power transmission auxiliary device 9 is substantially the same as the diameter of the power transmission resonance coil 4a, and the central axes of both coils are also arranged substantially coaxially. It is desirable. However, the effect of increasing the power transferable distance is such that when the diameter of the power transmission resonance coil 4a is d1, the diameter of the power reception resonance coil 4b is d2, and the diameter of the auxiliary coil 10 is d3, d1> d2 and d2 If the relationship <d3 is satisfied, it can be obtained accordingly. If the diameter d1 of the power transmission resonance coil 4a is larger than the diameter d2 of the power reception resonance coil 4b, the magnetic flux between the auxiliary coil 10 and the auxiliary coil 10 can be used. This is because if the diameter is larger than the diameter d2 of the resonance coil 4b, the magnetic flux between the resonance coil 4a for power transmission can be used.

  Here, in order to investigate the influence of the auxiliary coil 10, the result of VNA (vector network analyzer) measurement with a minute electric power will be described. The resonance frequency f1 of the power transmission device 1 was set by the capacitance value of a fixed capacitor provided as a resonance capacitor. Specifically, f1 = 12.1 MHz.

  First, the result of examining the change in the resonance frequency of the power transmission side resonance system when the resonance frequency f3 of the power transmission auxiliary device 9 is changed will be described. FIG. 2A shows an example of the arrangement of each coil. That is, the power transmission resonance coil 4a and the auxiliary coil 10 are arranged to face each other to form a power reception space having a length of 30 mm, and the VNA is connected to the loop coil 3a. The resonance frequency f3 is variable by adjusting the variable variable capacitor 11 for adjustment.

  FIG. 2B shows the VNA measurement result in this arrangement. In FIG. 2B, the horizontal axis represents the resonance frequency f3 of the power transmission auxiliary device 9, and the vertical axis represents the value of the resonance frequency ft of the power transmission side resonance system at the time of VNA measurement. FIG. 2C shows an output waveform diagram of VNA measurement when the resonance frequency f3 is 9 MHz, 12.1 MHz, and 16 MHz.

  For example, when f3 is adjusted to the same resonance frequency (12.1 MHz) as f1, two resonance frequencies appear centered on 12.1 MHz as shown in the waveform diagram of FIG. Combined state). The left resonance frequency on the low frequency side is described as ftL, and the right resonance frequency on the high frequency side is described as ftH. FIG. 2B shows a characteristic line corresponding to the resonance frequency ftL on the low frequency side and a characteristic line corresponding to the resonance frequency ftH on the high frequency side.

  As the resonance frequency f3 of the power transmission auxiliary device 9 is changed, the resonance frequency ftL on the low frequency side gradually shifts to the high frequency side, and finally approaches 12.1 MHz, which is the same as f1, as shown in FIG. As shown in c), the signal becomes larger. Although the resonance frequency ftH on the high frequency side gradually shifts to the high frequency side, the difference from the resonance frequency ftL on the low frequency side increases, and the signal level also decreases and approaches zero. As described above, by changing the resonance frequency f3 of the auxiliary resonator alone, the resonance frequency ft of the power transmission side resonance system can be changed.

  On the other hand, when the resonance frequency f3 is changed to the low frequency side, the resonance frequency ftH on the high frequency side gradually shifts to the low frequency side, and finally approaches the same 12.1 MHz as f1. However, the signal does not become so large as shown in FIG. 2C (a) as compared with the case of the resonance frequency ftL on the low frequency side. The resonance frequency ftL on the low frequency side also gradually shifts to the low frequency side, the difference from the resonance frequency ftH on the high frequency side becomes larger, the signal becomes smaller, and approaches zero.

  Next, the result of investigating the change of the power transmission efficiency when the resonance frequency f3 of the power transmission auxiliary device 9 is changed by the arrangement of the coils shown in FIG. 3A is shown. In the arrangement of FIG. 3A, the power receiving resonance coil 4b and the loop coil 3b are arranged in the power receiving space between the power transmitting resonance coil 4a and the auxiliary coil 10 in the arrangement of FIG. 2A. A VNA was connected to the loop coils 3a and 3b. The power transmission efficiency mentioned here is a numerical value between the power transmission resonance coil 4a and the power reception resonance coil 4b, and does not include the efficiency of a circuit or the like. The resonance frequency f2 of the power receiving device 2 is set by the capacitance value of a fixed capacitor provided as a resonance capacitor. Specifically, f2 = f1 = 12.1 MHz.

  The VNA measurement result in this arrangement is shown in FIG. 3B. FIG. 3B shows a characteristic line corresponding to the resonance frequency ftL on the low frequency side and a characteristic line corresponding to the resonance frequency ftH on the high frequency side. As can be seen from FIG. 3B, for example, in the case of f1 = f2 = f3 = 12.1 MHz (indicated by an arrow), the power transmission efficiency is as small as about 44%. When f3 is made larger than this, the power transmission efficiency corresponding to the resonance frequency ftL on the low frequency side is also increased. In the case of f3 = 16 MHz, a power transmission efficiency of about 64% is obtained.

  As described above, by setting the resonance frequency f3 of the power transmission auxiliary device 9 to be larger than f1 and f2, the resonance frequency ft at the time of power transmission can be made closer to the resonance frequency f2, and the power transmission efficiency at that time is also increased. Can be big.

  On the other hand, when the resonance frequency f3 is changed to the low frequency side, the power transmission efficiency corresponding to the resonance frequency ftH on the high frequency side increases. In the case of f3 = 5 MHz, a power transmission efficiency of about 46% is obtained. Thereby, by making the resonance frequency f3 of the power transmission auxiliary device 9 smaller than f1 and f2, the resonance frequency ft at the time of power transmission can be made closer to the resonance frequency f2, thereby increasing the power transmission efficiency at that time. . However, the value in the maximum region of the power transmission efficiency corresponding to the resonance frequency ftH on the high frequency side is smaller than the maximum region of the power transmission efficiency corresponding to the resonance frequency ftL on the low frequency side.

  From the above, when there is one power transmission device and one power receiving coil, the individual resonance frequencies of each device during power transmission are set so as to have a relationship of f1 ≠ f3. In particular, the case of f1 <f3 is preferable from the viewpoint of power transmission efficiency. The resonance frequency f2 of the power receiving device 2 is preferably the same as the resonance frequency f1 of the power transmission device 1, but may be different depending on circumstances.

  According to the results obtained as shown in FIGS. 2B and 3B, the resonance frequency ft of the power transmission side resonance system is adjusted regardless of the value of the resonance frequency f1 of the power transmission device 1 by adjusting the resonance frequency f3 of the power transmission auxiliary device 9. It can be easily changed. Thereby, it is easy to match the resonance frequency ft of the power transmission side resonance system with the resonance frequency f2 of the power receiving device 2.

  Therefore, the characteristics when the resonance frequency f1 of the power transmission device 1 and the resonance frequency f2 of the power reception device 2 are different depending on the arrangement of the coils illustrated in FIG. 4A were examined. 4A is an arrangement in which a power receiving resonance coil 4b and a loop coil 3b are arranged in a power receiving space between the power transmitting resonance coil 4a and the auxiliary coil 10 in the arrangement of FIG. 2A. A VNA was connected to the loop coils 3a and 3b.

  Here, the inherent resonance frequency f2 of the power receiving device 2 is fixed at 11.85 MHz, and the resonance frequency f1 of the power transmission device 1 is changed. In order to change the resonance frequency f1 of the power transmission device 1, a variable capacitor (hereinafter referred to as “variable capacitor”) 12 is connected to both ends of the power transmission resonance coil 4a separately from the fixed capacitor that is the resonance capacity of the power transmission resonator. . By manually adjusting the variable capacitor 12, the resonance frequency f1 of the power transmission device 1 was changed.

  The resonance frequency f1 of the power transmission device 1 was changed at 1 MHz intervals within a range of ± 2 MHz with reference to 11.85 MHz which is the resonance frequency f2 of the power reception device 2. Then, at each resonance frequency f1 of the power transmission device 1, the adjustment variable capacitor 11 of the power transmission auxiliary device 9 is set so that the power transmission efficiency at the resonance frequency f2 of the power reception device 2 is maximum (resonance frequency is 11.85 MHz). The resonance frequency f3 was adjusted by operating. The result of the experiment is shown in FIG. 4B.

  4B, the horizontal axis represents the value of the resonance frequency f1 of the power transmission device 1, and the vertical axis represents the power transmission efficiency between the power transmission device 1 and the power reception device 2. From this figure, it can be seen that the power transmission efficiency is maximized when the resonance frequency f1 of the power transmission device 1 is the same as the resonance frequency f2 of the power reception device 2 (f1 = f2 = 11.85 MHz). However, even when the resonance frequency f1 of the power transmission device 1 is increased to 12.85 MHz and 1 MHz (circles) (f1 ≠ f2), the power transmission efficiency is as large as 50% or more. That is, even if power transmission is performed using the power transmission device 1 and the power reception device 2 having different specific resonance frequencies, the resonance frequency ft of the power transmission side resonance system is adjusted using the power transmission auxiliary device 9 (resonance of the power reception device 2). It can be seen that high-efficiency power transmission is possible by bringing the frequency closer to f2.

  As for the configuration of the non-contact power transmission device, unlike the above-described experiment, the resonance frequency f1 of the power transmission device 1 is fixed, and the resonance frequency f2 of the power reception device 2 changes. Of course, in this case as well, high-efficiency power transmission is possible by adjusting the resonance frequency ft of the power transmission side resonance system using the power transmission auxiliary device 9 (closer to the resonance frequency f2 of the power receiving device 2).

<Embodiment 2>
A magnetic resonance type non-contact power transmission apparatus according to Embodiment 2 will be described with reference to FIGS. In the present embodiment, a configuration based on the same operation as in the first embodiment is used. That is, similarly to the arrangement shown in FIG. 4A, the power receiving resonance coil 4 b and the loop coil 3 b are arranged in the power receiving space between the power transmitting apparatus 1 and the power transmission auxiliary apparatus 9. Accordingly, elements similar to those described in the description of the arrangement shown in FIG. 4A are denoted by the same reference numerals, and the description is simplified.

  5A and 5B show an example of the arrangement of each coil. FIG. 5A is a schematic cross-sectional view. FIG. 5B is a front view of the adjustment coil 10 as viewed from the left side of the power receiving resonance coil 4b in FIG. 5A. In this configuration, the power receiving resonance coils 4bA and 4bB in the two power receiving devices A and B (not shown) are arranged in parallel in the power receiving space. Since the power receiving resonance coils 4bA and 4bB are sufficiently small, the two power receiving resonance coils 4bA and 4bB are disposed in an annular shape of the power transmission resonance coil 4a and the adjustment coil 10.

  If the configuration of the present embodiment is used, it is possible to match the resonance frequency ft of the power transmission side resonance system including the power transmission device 1 to the resonance frequency of the power reception devices A and B using the power transmission auxiliary device 9. The same effect can be obtained also when a plurality of power receiving apparatuses are arranged in excess of two. The power receiving resonators including the power receiving resonance coils 4bA and 4bB may have the same resonance frequency or may have different resonance frequencies.

  When power receiving devices A and B having substantially the same resonance frequency are used, charging by simultaneous power transmission is possible. When power receiving devices A and B having different resonance frequencies are used, selective power transmission is possible. Can be charged. In the following description, an operation of selective power transmission by one power transmission device 1 will be described by taking as an example a case where two power reception devices having different inherent resonance frequencies are used. 5A and 5B, the unique resonance frequency f2A of the power receiving apparatus A including the power receiving resonance coil 4bA is set to 12 MHz, and the specific resonance frequency f2B of the power receiving apparatus B including the power receiving resonance coil 4bB is set to 13.6 MHz. A case of setting will be described as an example.

  After the arrangement shown in FIGS. 5A and 5B, first, the power receiving resonance coil 4bB was set to an unloaded state, and the VNA was connected only to the power receiving resonance coil 4bA. Thereby, the power transmission characteristics were examined between the power transmission resonance coil 4a and the power reception resonance coil 4bA. Here, the measurement was performed by the same method as described with reference to FIGS. 4A and 4B.

  First, the resonance frequency f2A unique to the power receiving apparatus A was fixed at 12 MHz, and the resonance frequency f1 of the power transmission apparatus 1 was changed. In order to change the resonance frequency f1 of the power transmission device 1, a variable capacitor 12 was connected to both ends of the power transmission resonance coil 4a separately from the fixed capacitor that is the resonance capacity of the power transmission resonator. By manually adjusting the variable capacitor 12, the resonance frequency f1 of the power transmission device 1 was changed. Then, at each resonance frequency f1 of the power transmission device 1, the power transmission auxiliary device 9 is operated by operating the adjustment variable condenser 11 so that the power transmission efficiency at the resonance frequency f2A of the power reception device A is maximized (resonance frequency is 12 MHz). The resonance frequency f3 was adjusted. The result of the experiment is shown in FIG. 5C.

  In FIG. 5C, the horizontal axis represents the value of the resonance frequency f1 of the power transmission device 1, and the vertical axis represents the power transmission efficiency between the power transmission resonance coil 4a and the power reception resonance coil 4b. From this figure, it can be seen that the power transmission efficiency is maximum when the resonance frequency f1 of the power transmission device 1 and the resonance frequency f2A of the power reception device A are the same (f1 = f2 = 12 MHz). However, f2 ≠ f3.

  On the other hand, even when the resonance frequency f1 of the power transmission device 1 is increased by 13 MHz and 1 MHz (f1 ≠ f2), the power transmission efficiency is as high as 60% or more. That is, when power transmission is performed using the power transmission device 1 and the power reception device A having different specific resonance frequencies, the resonance frequency ft of the power transmission side resonance system is adjusted using the power transmission auxiliary device 9 (resonance of the power reception device A). It can be seen that high-efficiency power transmission is possible by bringing the frequency close to the frequency f2A. However, f2 ≠ f3.

  Next, in order to investigate the power transmission characteristics between the power transmission resonance coil 4a and the power reception resonance coil 4bB, the power reception resonance coil 4bA was set to an unloaded state, and the VNA was connected only to the power reception resonance coil 4bB. That is, the inherent resonance frequency f2B of the power receiving resonance coil 4bB was fixed at 13.6 MHz, and the resonance frequency f1 of the power transmission device 1 was changed by the variable condenser 12. Then, in each of the resonance frequencies f1 of the power transmission device 1, the adjustment variable capacitor 11 of the power transmission auxiliary device 9 is set so that the power transmission efficiency at the resonance frequency f2B of the power reception device B is maximized (the resonance frequency is 13.6 MHz). The resonance frequency f3 of the power transmission auxiliary device 9 was adjusted by operating. The result of the experiment is shown in FIG. 5D.

  5D, the horizontal axis represents the value of the resonance frequency f1 of the power transmission device 1, and the vertical axis represents the power transmission efficiency between the power transmission resonance coil 4a and the power reception resonance coil 4b. From this figure, it can be seen that the power transmission efficiency is maximized when the resonance frequency f1 of the power transmission device 1 and the resonance frequency f2B of the power reception device B are the same (f1 = f2 = 13.6 MHz). However, even if the resonance frequency f1 of the power transmission device 1 is different from the resonance frequency f2B of the power reception device B (f1 ≠ f2), the power transmission efficiency is as large as 60% or more. That is, when power transmission is performed using the power transmission device 1 and the power reception device B having different specific resonance frequencies, the resonance frequency ft of the power transmission side resonance system is adjusted using the power transmission auxiliary device 9 (resonance of the power reception device B). It can be seen that high-efficiency power transmission is possible by bringing the frequency close to the frequency f2B.

  From the above results, the resonance frequency f1 of the power transmission device 1 is fixed at 13.2 MHz (circled in the figure), and in either case, it is matched with the resonance frequency f2A of the power reception device A or the resonance frequency f2B of the power reception device B. It can be seen that a power transmission efficiency of 60% or more can be obtained. In this case, the resonance frequency f1 of the power transmission device 1 and the resonance frequencies f2A and f2B of the power reception devices A and B may be different (f1 ≠ f2A ≠ f2B).

  As described above, according to the contactless power transmission device of the present embodiment, for example, the resonance between the unique resonance frequency f2A of the power receiving device A = 12 MHz and the unique resonance frequency f2B of the power receiving device B = 13.6 MHz. By setting the resonance frequency f1 of the power transmission device 1 to be the frequency and adjusting the variable capacitor 11 for adjustment of the power transmission auxiliary device 9 to one of the resonance frequencies of the power receiving devices A and B, selective power transmission is possible. .

  According to this embodiment, in the case of selective power transmission in which a plurality of power receiving devices are arranged for one power transmitting device and power is transmitted to only one specific power receiving device among the power receiving devices, for example, the power receiving device For example, the value of each resonance frequency of each device in the case of two is set as follows. That is, the respective resonance frequencies are set to have a relationship of f2A ≠ f2B ≠ f3. The resonance frequency f1 of the power transmission device 1 may be the same as one of the resonance frequencies f2A and f2B of the power reception device, but is preferably different because it is not necessary to adjust the resonance frequency f1 of the power transmission device 1. In this case, the resonance frequency f1 of the power transmission device 1 is desirably in a frequency band between the resonance frequencies f2A and f2B of the power reception devices A and B.

  In the embodiment, when a plurality of power receiving devices are arranged in parallel to face the power transmitting device, it is desirable that the resonance coils of various power receiving devices do not overlap.

<Embodiment 3>
FIG. 6 is a cross-sectional view showing the magnetic resonance type non-contact power transmission apparatus according to the third embodiment. This non-contact power transmission device includes a case 13 of a decorative box type (or a music box type) and an openable / closable lid 14, and the power transmission device 1 is held inside the lower side of the housing 13. A power transmission auxiliary device 9 is held. A pedestal 15 for placing the power receiving device 2 is provided above the power transmitting device 1, and the power receiving device 2 (for example, a mobile phone or a hearing aid) can be mounted on the pedestal 15. And the power receiving apparatus 2 is arrange | positioned between the power transmission apparatus 1 and the power transmission auxiliary apparatus 9 by closing the cover 14. Non-contact power transmission is performed in this form.

  The housing 13 is provided with a high-frequency power driver 5 that converts power received from an AC power supply (AC 100 V) into power that can be transmitted, a control circuit 16 for impedance matching, and the like. Moreover, the electromagnetic shielding material 17 is arrange | positioned surrounding the area | region where the power transmission apparatus 1 and the power transmission auxiliary device 9 are arrange | positioned. In the state where the lid 14 is closed, the surroundings of the power transmission device 1, the power transmission auxiliary device 9, and the power reception device 2 are completely shielded from electromagnetic waves, and the electromagnetic waves are prevented from affecting the human body, which is safe.

  When power is transmitted by magnetic field resonance, it is conceivable to use a band of several MHz to several hundred MHz as a transmission frequency in practical use. Although the influence on the human body is less than that of the electric field resonance type, the influence on the human body must be taken into account depending on the value of the transmission power. Therefore, as in this embodiment, in order to prevent electromagnetic waves from leaking to the outside during non-contact power transmission, it is desirable to electromagnetically shield the entire coil so as to surround the power transmission / reception space. That is, in the case of a cosmetic box type, the resonance coils of the power transmission device 1 and the power reception device 2 and the auxiliary coil of the power transmission auxiliary device 9 are arranged in an electromagnetically closed space, and electromagnetic leakage to the outside It is set as the structure which prevents.

  A display 18 such as a display or LED is provided on the surface of the housing 13 as necessary. This is mainly for displaying the state of charge of a mobile phone or the like and incoming information such as mail. Further, a projection 19 for an interlock function is provided so that power transmission does not start unless the lid 14 is completely closed.

  In resonant power transmission, the magnetic field strength is maximized at the resonant frequency. The control circuit 16 may include a circuit for exchanging information with the power receiving device 2 and the power transmission auxiliary device 9, a circuit for obtaining position information of the power receiving device 2, and the like.

  The contactless power transmission device of the present embodiment is characterized in that the adjustment variable capacitor provided in the power transmission auxiliary device 9 is adjusted to match the resonance frequencies of the power transmission side resonance system and the power reception resonator during power transmission. It is. The auxiliary coil 10 is placed at a predetermined position with the lid 14 closed in advance, and the adjustment variable capacitor is adjusted so that the resonance frequency of the power transmission side resonance system and the resonance frequency of the power reception resonator are the same in that state. In other words, it is possible to start charging immediately when the lid 14 is put on. Alternatively, the adjustment variable condenser can be automatically or manually adjusted after the lid 14 is closed.

  In the present embodiment, the case 13 of the decorative box type is used, but the same effect can be obtained by using a box type or a desk drawer type. In other words, in the case of a cosmetic box type, it is difficult to exchange radio waves with the outside when the lid is closed. In this case, a box-type housing with an insertion port of the power receiving device is opened, and everything except this insertion port is electromagnetic. What is necessary is just to set it as the structure which provided the shield. However, the box type has an insertion port for the power receiving device, so there may be some leakage of electromagnetic waves to the outside. However, if an electromagnetic wave absorber sheet is attached to this insertion port, the impact on the human body will be reduced. Is done.

  In the above embodiment, a small device such as a mobile phone has been described as an example of the power receiving device 2. However, it goes without saying that the present invention can also be applied to a large power receiving device such as an electric vehicle.

  The non-contact power transmission device of the present invention can selectively perform non-contact power transmission with respect to a specific power receiving device, and can stabilize good power transmission over a long distance even when the power receiver is small. It is suitable for non-contact power transmission to small devices such as mobile phones and hearing aids, TVs and electric vehicles.

DESCRIPTION OF SYMBOLS 1 Power transmission device 2 Power reception device 3a, 3b Loop coil 4a Power transmission resonance coil 4b, 4bA, 4bB Power reception resonance coil 5 High frequency power driver 6 AC power source 7 Rectifier circuit 8 Rechargeable battery 9 Power transmission auxiliary device 10 Auxiliary coil 11 Adjustment capacitor ( Variable condenser for adjustment)
12 variable capacitor 13 housing 14 lid 15 pedestal 16 control circuit 17 electromagnetic shielding material 18 display 19 projection for interlocking

Claims (12)

A power transmission device having a power transmission resonator composed of a resonance coil for power transmission and a resonant capacitor;
A power receiving device having a power receiving resonator constituted by a power receiving resonance coil and a resonant capacitor;
In the non-contact power transmission device that transmits power from the power transmission device to the power reception device via magnetic field resonance between the power transmission resonance coil and the power reception resonance coil,
A power transmission auxiliary device including an auxiliary resonator that includes an auxiliary coil and a resonance capacitor and has a variable resonance frequency f3;
The power transmission auxiliary device is arranged to face the power transmission device, and a power reception space in which the power reception resonance coil is arranged can be formed between the power transmission resonance coil and the auxiliary coil.
By adjusting the resonance frequency f3, the resonance frequency ft of the power transmission side resonance system formed by the power transmission resonator and the auxiliary resonator can be adjusted.   The contactless power transmission device according to claim 1, wherein the resonance capacitance of the power transmission auxiliary device is configured by a variable capacitor, and the resonance frequency f <b> 3 of the auxiliary resonator can be adjusted by adjusting the variable capacitor.   The resonance capacitance of the auxiliary resonator is configured by a plurality of fixed capacitors each having a different capacitance value, and the fixed capacitor selectively connected to the auxiliary coil is switched to change the resonance frequency f3 of the auxiliary resonator. The contactless power transmission device according to claim 1, which is adjustable.   The non-contact power transmission device according to claim 1, wherein a diameter d1 of the power transmission resonance coil, a diameter d2 of the power reception resonance coil, and a diameter d3 of the auxiliary coil satisfy a relationship of d1> d2 and d2 <d3.   The non-contact power transmission apparatus according to claim 4, wherein d1 = d3 and d1> d2 are satisfied.   The non-contact power transmission apparatus according to claim 4, wherein a central axis of the power transmission resonance coil, a central axis of the auxiliary coil, and a central axis of the power reception resonance coil are on the same axis.   The contactless power transmission device according to claim 1, wherein one power receiving device is arranged for one power transmission device, and the resonance frequency f3 is set under a condition of f1 ≠ f3.   The contactless power transmission device according to claim 7, wherein the resonance frequency f3 is set under a condition of f1 <f3.   The non-contact according to claim 1, wherein a plurality of power receiving devices are arranged for one power transmitting device, and the resonance frequencies f2 of the power receiving resonators of the plurality of power receiving devices are all different and f2 ≠ f3. Power transmission device.   A plurality of power receiving devices are arranged for one power transmitting device, and at least some of the power receiving resonators of the plurality of power receiving devices have different resonance frequencies f2 and f1 ≠ f2. The contactless power transmission device according to 1. Holding the power transmission device and the power transmission auxiliary device, comprising a housing capable of setting the mutual positional relationship between the power transmission device and the power transmission auxiliary device so that the power receiving space is formed,
The power receiving device can be detachably attached to the power receiving space,
The non-contact power transmission apparatus according to claim 1, wherein power transmission is performed in a state where at least surroundings of the power transmission resonance coil, the auxiliary coil, and the power reception resonance coil are electromagnetically shielded in the housing. A power transmission device having a power transmission resonator constituted by a power transmission resonance coil and a resonance capacitor, and a power reception device having a power reception resonator constituted by a power reception resonance coil and a resonance capacitance, the power transmission resonance coil and the power reception In a non-contact power transmission method for transmitting power from the power transmission device to the power reception device via magnetic field resonance between resonance coils for use,
Further using a power transmission auxiliary device having an auxiliary resonator that is constituted by an auxiliary coil and a resonance capacitor and whose resonance frequency f3 is variable,
The power transmission auxiliary device is arranged to face the power transmission device, and the power reception resonance coil is arranged in a power reception space formed between the power transmission resonance coil and the auxiliary coil,
A non-contact power transmission method characterized by adjusting the resonance frequency f3 to adjust the resonance frequency ft of the power transmission side resonance system formed by the power transmission resonator and the auxiliary resonator to perform power transmission.

Images