JP2012023929A - Resonance coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resonance coil capable of easily adjusting for the purpose of obtaining desirable electrical characteristics.SOLUTION: A resonance coil 100, which is designed to transmit power to a separate coil or receive power from the separate coil by resonating with the separate coil via an electromagnetic field, includes: a first coil section 110 having an open end; a second coil section 120 having an open end; a first tap 151 disposed at one end of the first coil section 110; a second tap 152 disposed at one end of the second coil section 120; and a capacitor 130 disposed between the first tap 151 and the second tap 152.

Description

  The present invention relates to a resonance coil used for magnetic resonance wireless power transmission.

  In recent years, development of technology for transmitting electric power (electric energy) wirelessly without using a power cord or the like has become active. Among wireless transmission methods, there is a technique called magnetic resonance as a technology that has attracted particular attention. This magnetic resonance method was proposed by a research group of Massachusetts Institute of Technology in 2007, and a technology related to this is disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-501510.

  The magnetic resonance type wireless power transmission system efficiently sets the resonance frequency of the power transmission resonance coil and the resonance frequency of the power reception resonance coil to efficiently transfer energy from the power transmission resonance coil to the power reception resonance coil. One of the major features is that the power transmission distance is several tens of centimeters to several meters.

  FIG. 8 is a diagram illustrating a configuration example of a conventional wireless power transmission system. An outline of the power transmission system shown in FIG. 8 will be described. A power supply from the power supply 10 is obtained, and an AC waveform for transmission is generated in the power supply unit 20 including an inverter and the like, and this is input to the impedance matching unit 30. The waveform impedance-matched by the impedance matching unit 30 is supplied to the power transmission resonance coil 200 via the power transmission path 50. As shown in FIG. 8, the power transmission resonance coil 200 is composed of a pair of helical coils having one end portion to which power is supplied and an open end portion.

The power receiving resonance coil 200 ′ having a symmetrical relationship with the power transmission resonance coil 200 receives power from the power transmission resonance coil 200 by magnetic resonance. The received power is rectified by the rectifier 70 through the impedance matching unit 60 through the power transmission path 50 and supplied to the load 80.
Special table 2009-501510

  By the way, the resonance coils 200 and 200 'used in the above-described conventional power transmission system have a problem that adjustment for obtaining desired electrical characteristics is difficult.

  In order to solve the above problem, the invention according to claim 1 is a resonance coil that transmits and receives electrical energy by resonating via an electromagnetic field, and includes a first coil portion having an open end and an open end. A second coil portion; a first tap portion provided at one end of the first coil portion; a second tap portion provided at one end of the second coil portion; the first tap portion and the second tap. And a capacitor provided between the first and second parts.

  The invention according to claim 2 is the resonance coil according to claim 1, wherein the capacitor is selected so that power transmission efficiency is maximized in a system in which the resonance coil is used. .

  According to a third aspect of the present invention, in the resonance coil according to the first aspect, the capacitor is selected so that an impedance of the resonance coil becomes a predetermined value in a system in which the resonance coil is used. It is characterized by.

  The invention according to claim 4 is the resonance coil according to claim 1, wherein power is supplied to the first tap portion and the second tap portion, or the first tap portion and the second tap portion. The capacitor is selected such that the impedance is the same as the impedance of the power transmission line.

  The invention according to claim 5 is characterized in that, in the resonance coil according to claim 1, the third coil portion is selected such that Q of the resonance coil becomes a predetermined value.

  The invention according to claim 6 is the resonance coil according to claim 1, wherein the capacitor is selected such that a resonance point of the resonance coil has a predetermined value.

  The invention according to claim 7 is characterized in that, in the resonance coil according to any one of claims 1 to 5, a capacitor capable of changing a capacitance is used as the capacitor.

  As described above, according to the resonance coil of the present invention, it is possible to easily perform adjustment for obtaining desired electrical characteristics.

  Further, according to the resonance coil according to the present invention, the loss between the resonance coil 100 and the power transmission path 50 can be minimized, and power can be efficiently supplied from the power transmission path 50 to the resonance coil. Alternatively, it is possible to efficiently transmit the power received by the resonance coil.

  Moreover, according to the resonance coil according to the present invention, it is possible to easily adjust the desired Q and resonance point of the resonance coil 100.

It is a figure which shows the outline of a block structure of the electric power transmission system with which the resonance coil which concerns on embodiment of this invention was used. It is a figure which shows the application example of the resonance coil which concerns on embodiment of this invention. It is a figure explaining the structure of the resonance coil which concerns on embodiment of this invention. It is a figure which shows the equivalent circuit of the resonance coil which concerns on embodiment of this invention. It is a figure which shows the change of the impedance characteristic accompanying the change of the capacitor in the resonance coil which concerns on embodiment of this invention. It is a figure which shows the modification of the capacitor provided between the taps in the resonance coil which concerns on embodiment of this invention. It is a figure explaining the structure of the resonance coil which concerns on other embodiment of this invention. It is a figure which shows the structural example of the conventional wireless power transmission system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of a block configuration of a power transmission system using a resonance coil according to an embodiment of the present invention, and FIG. 2 is a diagram showing an application example of the resonance coil according to the embodiment of the present invention. It is.

A resonance coil as related to the present invention is suitable for use in a system for supplying power to a vehicle such as an electric vehicle (EV) or a hybrid electric vehicle (HEV) as shown in FIG. Of course, it can also be used for power transmission in this system.

  In the application example of the resonance coil shown in FIG. 2, a power transmission resonance coil 100 is provided on the ground portion, and a power reception resonance coil 100 ′ provided on the vehicle side such as EV or HEV is provided. When power is supplied to the vehicle, the vehicle adjusts the position of the vehicle so that the central axis of the resonance coil 100 and the central axis of the resonance coil 100 ′ substantially overlap, and the resonance coil 100 passes through the resonance coil 100 ′. The power is preferably received and stored in a power storage device mounted on a vehicle (not shown) or the like.

  FIG. 1 shows a block configuration of a general power transmission system to which a resonance coil is applied. The load 60 in such a system is used as a power supply system for a vehicle as described above by using a power storage device. Is possible. Next, the power transmission system shown in FIG. 1 will be described. In the power supply unit 20 composed of an inverter or the like, power from the power source 10 is obtained and converted into AC power for transmission, which is input to the impedance matching unit 30. The frequency of AC power output from the power supply unit 20 is several hundred kHz to several tens of MHz. The impedance matching unit 30 is an LC circuit composed of a variable capacitor and a variable inductor, and the waveform of which impedance matching is taken by the impedance matching unit 30 is used for power transmission via a power transmission path 50 such as a feeder line. The resonance coil 100 is supplied. As shown in FIG. 1, the resonance coil 100 for power transmission has a structure in which a power feeding tap is provided on a helical coil having two open ends.

  A power receiving resonance coil 100 ′ having a symmetrical relationship with the power transmission resonance coil 100 receives power from the resonance coil 100 by a magnetic resonance method. The electric power received by the resonance coil 100 ′ is rectified by the rectifier 70 through the impedance matching unit 60 via the power transmission path 50 and supplied to the load 80.

  Note that the resonance coil 100 according to the present embodiment can be used for either a balanced circuit or an unbalanced circuit. That is, a balanced-unbalanced converter such as a balun can be appropriately used in the circuit configuration shown in FIG.

  Next, the resonance coil according to this embodiment will be described in more detail. FIG. 3 is a diagram illustrating the configuration of the resonance coil according to the embodiment of the present invention. In the following description, since the resonance coil 100 and the resonance coil 100 ′ have no particular difference except for the symmetrical relationship, the resonance coil 100 will be described as an example.

  The resonant coil 100 includes a first coil portion 110 from the first open end 141 to the first tap 151, a second coil portion 120 from the second tap 152 to the second open end 142, a first tap 151, and a second tap. And a capacitor between the tap 152 and the capacitor. As the conductive material constituting the first coil part 110 and the second coil part 120, a litz wire or the like can be used.

  In the first tap 151, the first coil unit 110 and one end of the capacitor 130 are connected, and in the second tap 152, the second coil unit 120 and the other end of the capacitor 130 are connected. ing.

  The power transmission path 50 is connected to the first tap 151 and the second tap 152, and power is supplied to the first tap 151 and the second tap 152 or received from the first tap 151 and the second tap 152. Or take out.

The capacitor 130 provided between the first tap 151 and the second tap 152 is
It is configured to be appropriately selectable according to desired electrical characteristics. Because of such a configuration, the resonance coil 100 according to the present embodiment can enjoy the advantage that adjustment for obtaining desired electrical characteristics is facilitated.

  FIG. 3A shows a case where the respective tap positions are set so that the capacitor 130 provided between the first tap 151 and the second tap 152 has the first capacitance. B) shows a case where each capacitor is selected so that the capacitor 131 provided between the first tap 151 and the second tap 152 has a second capacitance larger than the first capacitance. The resonance coil according to the present embodiment can easily change its electrical characteristics simply by selecting a capacitor in this way.

  As shown in FIG. 3, by selecting a capacitor between the first tap 151 and the second tap 152, each equivalent circuit can be changed as shown in FIG. FIG. 4 is a diagram showing an equivalent circuit of the resonance coil according to the embodiment of the present invention. FIG. 4 (A) is an equivalent circuit corresponding to FIG. 3 (A), and FIG. It is an equivalent circuit corresponding to B).

The equivalent circuit formed by the first coil unit 110 and the second coil unit 120 in FIG. 3A is L ₁₁ and C ₁₁ connected in parallel, and between the first tap 151 and the second tap 152. An equivalent circuit formed by the capacitor 130 is C ₂₁ connected in parallel.

On the other hand, the equivalent circuit formed by the first coil unit 110 and the second coil unit 120 in FIG. 3B is L ₁₁ and C ₁₁ connected in parallel, and the first tap 151 and the second tap 152 An equivalent circuit formed by the capacitor 131 is C ₂₂ connected in parallel.

  In any case, the C component in the equivalent circuit formed by the first coil unit 110 and the second coil unit 120 is the floating capacity between the coil wires. Also, the size of the circuit element depicted in FIG. 4 is roughly proportional to the inductance value and the capacitance value.

  4A is an equivalent circuit corresponding to FIG. 3A, and that FIG. 4B is an equivalent circuit corresponding to FIG. 3B is obtained by analyzing impedance characteristics. This is the findings.

As can be seen from FIGS. 3 and 4, for example, by changing the capacitor from FIG. 3 (A) to FIG. 3 (B), C ₂₁ can be set to a larger C without changing L ₁₁ and C _11. Take possible to change to ₂₂ .

  FIG. 5 is a diagram showing a change in impedance characteristics accompanying a change of the capacitor in the resonance coil according to the embodiment of the present invention. FIG. 5A is a diagram showing the entire impedance characteristic, and FIG. 5B is an enlarged view of a portion where the imaginary part of the impedance intersects with the axis. In the figure, the solid line indicates the real part of the impedance, the dotted line indicates the imaginary part of the impedance before the change of the capacitor, and the alternate long and short dash line indicates the imaginary part of the impedance after the change of the capacitor.

  According to the resonance coil according to the present embodiment, for example, as shown in FIG. 5, it is possible to change the resonance point where the (imaginary part) of the impedance = 0, and easily change the desired electrical characteristics. You can see that it is possible.

Here, the concept for selecting a capacitor between the first tap 151 and the second tap 152 in the resonance coil 100 according to the present embodiment will be described. One way of thinking is to select the capacitor so that the overall power transmission efficiency is maximized in a system in which the resonance coil 100 as shown in FIG. 1 is used. . That is, in the system shown in FIG. 1, the inverter efficiency in the power supply unit 20, the wireless transmission efficiency between the resonance coil 100 and the resonance coil 100 ′, the transmission line efficiency of the power transmission line 50, the impedance matching unit 30, and the impedance matching unit 60 The idea is to select capacitors so that the overall efficiency including the impedance matching device efficiency is maximized. According to the resonance coil 100 according to the present embodiment, the maximum power transmission efficiency can be obtained in a system in which the resonance coil 100 is used.

  Next, in the resonance coil 100 according to the present embodiment, a different concept from the above when selecting a capacitor between the first tap 151 and the second tap 152 will be described. One way of thinking is to select the capacitor so that the impedance of the resonance coil 100 has a predetermined value. That is, the capacitor is selected so that the impedance of the resonance coil 100 becomes a predetermined value that matches, for example, the impedance (for example, 50Ω or 75Ω) of a feeder line that is generally used as the power transmission line 50. This is the idea. In this way, when the capacitor is selected so that the impedance of the resonance coil 100 becomes a predetermined value (for example, the same value as the impedance of the power transmission line 50), power feeding from the power transmission line 50 to the resonance coil 100, resonance In power feeding from the coil 100 to the power transmission line 50, there is a merit that the loss between the resonance coil 100 and the power transmission line 50 is minimized.

  Here, in the resonance coil 100 according to the present embodiment, a different concept from the above when selecting a capacitor between the first tap 151 and the second tap 152 will be described. One way of thinking is that the capacitor is selected so that the impedance of the resonance coil 100 is the same as the impedance of the power transmission line 50. That is, the concept is that the capacitor is selected so that the impedance of the resonance coil 100 matches the impedance (for example, 50Ω or 75Ω) of a feeder line that is generally used as the power transmission line 50. When the capacitor is selected so that the impedance of the resonance coil 100 is the same as the impedance of the power transmission line 50, power is supplied from the power transmission line 50 to the resonance coil 100, and power is supplied from the resonance coil 100 to the power transmission line 50. In power feeding, there is a merit that the loss between the resonance coil 100 and the power transmission line 50 is minimized.

  Here, in the resonance coil 100 according to the present embodiment, a different concept from the above when selecting a capacitor between the first tap 151 and the second tap 152 will be described. One of such ideas is that the capacitor is selected so that the Q of the resonance coil 100 has a predetermined value (more specifically, the highest value). Here, Q of the resonance coil 100 is a quality factor. If the capacitor is selected so that the Q of the resonance coil 100 has a high value, there is an advantage that the loss can be minimized in the resonance phenomenon of the resonance coil 100.

  Here, in the resonance coil 100 according to the present embodiment, a different concept from the above when selecting a capacitor between the first tap 151 and the second tap 152 will be described. One of such ideas is that the capacitor is selected so that the resonance point of the resonance coil 100 has a predetermined value. Considering FIG. 1, the energy transmission efficiency becomes the highest when the resonance point of the resonance coil 100 on the power transmission side and the resonance point of the resonance coil 100 ′ on the power reception side coincide with each other. According to this, it is possible to maximize the wireless transmission efficiency.

Next, the first tap 151 and the second tap 15 in the resonance coil 100 according to the present embodiment.
2 will be described. FIG. 6 is a view showing a modification of the capacitor provided between the taps in the resonance coil according to the embodiment of the present invention.

  In the modification shown in FIG. 6, a capacitor element (variable capacitor or the like) whose capacitance can be changed is provided as the capacitor 133. Also with such a capacitor 133, various electrical characteristics of the resonance coil 100 can be actively changed, and the same effects as those of the embodiments described so far can be enjoyed.

  As described above, according to the resonance coil of the present invention, it is possible to easily perform adjustment for obtaining desired electrical characteristics.

  Further, according to the resonance coil according to the present invention, the loss between the resonance coil 100 and the power transmission path 50 can be minimized, and power can be efficiently supplied from the power transmission path 50 to the resonance coil. Alternatively, it is possible to efficiently transmit the power received by the resonance coil.

  Moreover, according to the resonance coil according to the present invention, it is possible to easily adjust the desired Q and resonance point of the resonance coil 100.

  Next, a resonance coil 100 according to another embodiment of the present invention will be described. FIG. 10 is a diagram illustrating the configuration of a resonance coil 100 according to another embodiment of the present invention. The resonance coil 100 described so far is a coil wound spirally around a virtual coil axis extending in one direction. However, the resonance coil 100 according to another embodiment has a predetermined plane P. It has a spiral shape inside.

  The resonance coil 100 according to another embodiment includes a first coil portion 110 from the first open end 141 on the spiral innermost periphery side to the first tap 151, and a second open end on the spiral outermost periphery side from the second tap 152. The second coil unit 120 up to 142 and the capacitor 134 between the first tap 151 and the second tap 152 are configured. The first coil part 110 and the second coil part 120 are both spiral coils configured in the plane P, and for example, a litz wire or the like can be used as a conductive material forming these coils.

  In the first tap 151, the first coil unit 110 and one end of the capacitor 134 are connected, and in the second tap 152, the second coil unit 120 and the other end of the capacitor 134 are connected. ing. Further, the first coil part 110 and the second coil part 120 are formed to have substantially the same coil length.

    In the resonance coil 100 according to another embodiment, the power transmission path 50 is connected to the first tap 151 and the second tap 152, and power is supplied to the first tap 151 and the second tap 152, The power received from the first tap 151 and the second tap 152 is taken out.

  Further, the capacitor 134 provided between the first tap 151 and the second tap 152 is configured to be appropriately selectable according to desired electrical characteristics. Because of such a configuration, the resonance coil 100 according to the present embodiment can enjoy the advantage that adjustment for obtaining desired electrical characteristics is facilitated. Also, the resonance coil 100 according to the present embodiment can achieve the same effects as those of the embodiments described so far.

Note that the first tap 151 and the second tap 152 are in the radial direction of the spiral coil when power is supplied to the resonance coil 100 from the power transmission path 50 such as a feeder line or power is received from the resonance coil 100. It is desirable that they are close to each other.

DESCRIPTION OF SYMBOLS 10 ... Power supply, 20 ... Power supply part, 30 ... Impedance matching device, 50 ... Power transmission line, 60 ... Impedance matching device, 70 ... Rectifier, 80 ... Load, DESCRIPTION OF SYMBOLS 100, 100 '... Resonance coil, 110 ... 1st coil part, 120 ... 2nd coil part, 130, 131, 133, 134 ... Capacitor, 141 ... 1st open end, 142 ... 2nd open end, 151 ... 1st tap, 152 ... 2nd tap

Claims (7)

A resonance coil that transmits and receives electrical energy by resonating through an electromagnetic field,
A first coil portion having an open end;
A second coil portion having an open end;
A first tap portion provided at one end of the first coil portion;
A second tap portion provided at one end of the second coil portion;
A resonance coil comprising: a capacitor provided between the first tap portion and the second tap portion. The resonance coil according to claim 1, wherein the capacitor is selected so that power transmission efficiency is maximized in a system in which the resonance coil is used. 2. The resonance coil according to claim 1, wherein the capacitor is selected so that impedance of the resonance coil becomes a predetermined value in a system in which the resonance coil is used. Power is supplied to the first tap portion and the second tap portion, or has a power transmission line that transmits power from the first tap portion and the second tap portion,
The resonance capacitor according to claim 1, wherein the capacitor is selected such that an impedance of the resonance coil is the same as an impedance of the power transmission line. 2. The resonance coil according to claim 1, wherein the third coil portion is selected such that a Q of the resonance coil has a predetermined value. 2. The resonance coil according to claim 1, wherein the capacitor is selected such that a resonance point of the resonance coil has a predetermined value. The resonance coil according to claim 1, wherein a capacitor whose capacitance can be changed is used as the capacitor.

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