JP5930182B2 - antenna - Google Patents

Description

  The present invention relates to an antenna that is used in a magnetic resonance wireless power transmission system and receives power or transmits power.

  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 uses an antenna having the same resonance frequency of the power transmission side antenna as that of the power reception side antenna and a high Q value (100 or more), so that the power transmission side antenna is changed to the power reception side antenna. On the other hand, energy transmission is performed efficiently, and one of the major features is that the power transmission distance can be several tens of centimeters to several meters.

Some proposals have been made on the specific configuration of the antenna used in the above-described magnetic resonance type wireless power transmission system. For example, Patent Document 2 (Japanese Patent Application Laid-Open No. 2010-73976) discloses a structure of a communication coil provided in each of the power feeding circuit and the power receiving circuit of a wireless power transmission apparatus that wirelessly transmits power from the power feeding circuit to the power receiving circuit. A printed circuit board made of a material having a relative dielectric constant greater than 1, a primary coil provided on the first layer of the printed circuit board and formed of a conductive pattern forming at least one loop, and a second layer of the printed circuit board And a resonance coil formed of a conductive pattern having a spiral shape. The communication coil structure of the wireless power transmission device is disclosed.
Special table 2009-501510 JP 2010-73976 A

  When the magnetic resonance type power transmission system as described above is used for power supply to vehicles such as an electric vehicle (EV) and a hybrid electric vehicle (HEV), a power transmission antenna is embedded in the ground and receives power. It is assumed that the antenna for use is laid out on the bottom of the vehicle. However, in the coil structure described in Patent Document 1, the optimum design for installation at the bottom of a vehicle made of a metal body is not made. When this is used at the bottom of the vehicle, the power transmission efficiency is suppressed. It was a problem of being.

In order to solve the above problem, the invention according to claim 1 is a coil body in which a predetermined coil pattern conductive portion is formed on an insulating base material having a main surface, and the coil body on the coil body. a ferrite substrate that is disposed are a first distance apart, have a, an aluminum substrate that is disposed the ferrite substrate and being a second distance apart on the ferrite substrate, the first distance is the first It is characterized by being longer than 2 distances .

The invention according to claim 2 is the antenna according to claim 1, wherein when the projection is performed in a direction perpendicular to the main surface, the projection formed by the coil pattern conductive portion is the same as that of the ferrite base material. The projection formed by the ferrite base material is included in the projection formed by the aluminum base material.

The invention according to claim 3 is the antenna according to claim 1 or 2 , wherein the thickness of the ferrite base is set so that the amount of magnetic flux passing through the ferrite base is equal to or less than the saturation magnetic flux. It is characterized by doing.

According to a fourth aspect of the present invention, in the antenna according to any one of the first to third aspects, the thickness of the aluminum base is a thickness that blocks magnetic flux leaking from the ferrite base. It is characterized by doing.

  An antenna according to the present invention includes a ferrite base material disposed on a coil body and spaced apart from the coil body by a first distance, and an aluminum base material disposed on the ferrite base material and spaced apart from the ferrite base material by a second distance; Thus, even when an antenna is mounted on the bottom surface of the vehicle, it is possible to suppress the influence of a metal object constituting the vehicle main body and efficiently perform power transmission.

1 is a block diagram of a power transmission system in which an antenna according to an embodiment of the present invention is used. It is a figure which shows the inverter part of an electric power transmission system. 1 is an exploded perspective view of a power receiving antenna 201 according to a first embodiment of the present invention. It is a schematic diagram of the cross section which shows the mode of the electric power transmission by the power receiving antenna 201 which concerns on 1st Embodiment of this invention. It is a figure which shows the power transmission efficiency data of this invention and a comparative example. It is a figure explaining the conditions in data acquisition. It is a disassembled perspective view of the receiving antenna 201 which concerns on 2nd Embodiment of this invention. It is a schematic diagram of the cross section which shows the mode of the electric power transmission by the power receiving antenna 201 which concerns on 2nd Embodiment of this invention. It is a figure which shows the power transmission efficiency data of this invention and a comparative example. It is a figure explaining the conditions in data acquisition. It is a figure which shows the relationship between the impedance of an antenna, and transmission efficiency.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a power transmission system in which an antenna according to an embodiment of the present invention is used. The antenna according to the present invention can be applied to both a power receiving antenna and a power transmitting antenna constituting the power transmission system. However, in the following embodiments, the antenna of the present invention is used as the power receiving antenna. The applied example will be described.

As a power transmission system using the antenna of the present invention, for example, a system for charging a vehicle such as an electric vehicle (EV) or a hybrid electric vehicle (HEV) is assumed. Since the electric power transmission system transmits electric power to the vehicle as described above in a non-contact manner, the electric power transmission system is provided in a stop space where the vehicle can be stopped. The stop space, which is a vehicle charging space, is configured such that the power transmission antenna 105 and the like are buried in the ground. A user of the vehicle stops the vehicle in a stop space where the power transmission system is provided, and makes the power reception antenna 201 mounted on the vehicle and the power transmission antenna 105 face each other to thereby generate power from the power transmission system. Receive power. When the vehicle is stopped in the stop space, the power receiving antenna 201 mounted on the vehicle has a positional relationship with the highest transmission efficiency with respect to the power transmission antenna 105.

  In the power transmission system, when power is efficiently transmitted from the power transmission antenna 105 on the power transmission system 100 side to the power reception antenna 201 on the power reception side system 200 side, the resonance frequency of the power transmission antenna 105 and the resonance frequency of the power reception antenna 201 are By making the same, energy transmission is efficiently performed from the power transmission side antenna to the power reception side antenna.

  The AC / DC conversion unit 101 in the power transmission system 100 is a converter that converts an input commercial power source into a constant direct current. The output from the AC / DC converter 101 is boosted to a predetermined voltage in the high voltage generator 102. Setting of the voltage generated by the voltage adjustment unit 102 can be controlled from the main control unit 110.

The inverter unit 103 generates a predetermined AC voltage from the high voltage supplied from the high voltage generation unit 102 and inputs it to the matching unit 104. FIG. 2 is a diagram illustrating an inverter unit of the power transmission system. For example, as shown in FIG. 2, the inverter unit 103 includes four field effect transistors (FETs) composed of Q _{A to} Q _D connected in a full bridge system.

In the present embodiment, between the connection portion T1 between the switching elements Q _A and Q _B connected in series and the connection portion T2 between the switching elements Q _C and Q _D connected in series. The matching device 104 is connected to the switching element Q _A.
When the switching element Q _D is on, the switching element Q _B and the switching element Q _C are off. When the switching element Q _B and the switching element Q _C are on, the switching element Q _A and the switching element Q _D are off. As a result, a rectangular wave AC voltage is generated between the connection portion T1 and the connection portion T2. In the present embodiment, the range of the frequency of the rectangular wave generated by switching of each switching element is about several hundred kHz to several thousand kHz.

Drive signals for the switching elements Q _{A to} Q _D constituting the inverter unit 103 as described above are input from the main control unit 110. The frequency for driving the inverter unit 103 can be controlled from the main control unit 110.

  The matching unit 104 is composed of a passive element having a predetermined circuit constant, and receives an output from the inverter unit 103. The output from the matching unit 104 is supplied to the power transmission antenna 105. The circuit constants of the passive elements constituting the matching unit 104 can be adjusted based on a command from the main control unit 110. The main control unit 110 instructs the matching unit 104 so that the power transmitting antenna 105 and the power receiving antenna 201 resonate.

  The power transmission antenna 105 is composed of a coil having an inductive reactance component, and resonates with the vehicle-mounted power reception antenna 201 arranged so as to face each other, so that the electric energy output from the power transmission antenna 105 is received by the power reception antenna. 201 can be sent.

The main control unit 110 of the power transmission system 100 is a general-purpose information processing unit that includes a CPU, a ROM that holds a program that runs on the CPU, and a RAM that is a work area of the CPU. The main control unit 110 operates in cooperation with the components connected to the main control unit 110 shown in the figure.

  The communication unit 120 is configured to perform wireless communication with the vehicle-side communication unit 220 so that data can be transmitted to and received from the vehicle. Data received by the communication unit 120 is transferred to the main control unit 110, and the main control unit 110 can transmit predetermined information to the vehicle side via the communication unit 120.

  Next, a configuration provided on the vehicle side will be described. In the system on the power receiving side of the vehicle, the power receiving antenna 201 receives electric energy output from the power transmitting antenna 105 by resonating with the power transmitting antenna 105. Such a power receiving antenna 201 is adapted to be attached to the bottom portion of the vehicle.

  The AC power received by the power receiving antenna 201 is rectified by the rectification unit 202, and the rectified power is stored in the battery 204 through the charge control unit 203. The charging control unit 203 controls the storage of the battery 204 based on a command from the main control unit 210. In addition, the charging control unit 203 is configured to perform the remaining amount management of the battery 204 and the like.

  The main control unit 210 is a general-purpose information processing unit that includes a CPU, a ROM that holds programs that run on the CPU, and a RAM that is a work area of the CPU. The main controller 210 operates in cooperation with the components connected to the main controller 210 shown in the figure.

  The interface unit 230 is provided in the driver's seat of the vehicle and provides predetermined information to the user (driver) or accepts operation / input from the user. A touch panel, a speaker, and the like. When a predetermined operation by the user is executed, it is sent as operation data from the interface unit 230 to the main control unit 210 and processed. Further, when providing predetermined information to the user, display instruction data for displaying the predetermined information is transmitted from the main control unit 210 to the interface unit 230.

  Further, the vehicle-side communication unit 220 is configured to perform wireless communication with the power transmission-side communication unit 120 and to transmit and receive data to and from the power transmission-side system. Data received by the communication unit 220 is transferred to the main control unit 210, and the main control unit 210 can transmit predetermined information to the power transmission system side via the communication unit 220.

  In the power transmission system, a user who wants to receive power inputs the information indicating that charging is performed from the interface unit 230 by stopping the vehicle in the stop space where the power transmission side system as described above is provided. Receiving this, the main control unit 210 obtains the remaining amount of the battery 204 from the charge control unit 203 and calculates the amount of power necessary for charging the battery 204. The calculated amount of power and information to request power transmission are transmitted from the vehicle side communication unit 220 to the communication unit 120 of the power transmission side system. The main control unit 110 of the power transmission side system that has received the information controls the high voltage generation unit 102, the inverter unit 103, and the matching unit 104 to transmit power to the vehicle side.

  Next, a specific configuration of the antenna used in the power transmission system 100 configured as described above will be described. Hereinafter, although the example which employ | adopted the structure of this invention for the power receiving antenna 201 is demonstrated, the antenna of this invention is applicable also to the power transmission antenna 105. FIG.

  FIG. 3 is an exploded perspective view of the power receiving antenna 201 according to the first embodiment of the present invention, and FIG. 4 is a schematic cross-sectional view showing a state of power transmission by the power receiving antenna 201 according to the first embodiment of the present invention. The arrows in FIG. 4 schematically show the lines of magnetic force. In the following embodiments, a rectangular flat plate is described as an example of the coil body 270, but the antenna of the present invention is not limited to such a coil. For example, a circular flat plate or the like can be used as the coil body 270. Such a coil body 270 functions as a magnetic resonance antenna unit in the power receiving antenna 201. This “magnetic resonance antenna section” includes not only the inductance component of the coil body 270 but also a capacitance component based on its floating capacity, or a capacitance component based on an intentionally added capacitor.

  The case body 260 is used for housing the coil body 270 having the inductive reactance component of the power receiving antenna 201. The case body 260 has a box shape having an opening made of a resin such as polycarbonate. Side plate portions 262 are provided from the respective sides of the rectangular bottom plate portion 261 of the case body 260 so as to extend in a direction perpendicular to the bottom plate portion 261. An upper opening 263 that is surrounded by the side plate 262 is formed above the case body 260. The power receiving antenna 201 packaged in the case body 260 is attached to the vehicle main body on the upper opening 263 side. In order to attach the case body 260 to the vehicle main body, any conventionally known method can be used. A flange member or the like may be provided around the upper opening 263 in order to improve attachment to the vehicle main body.

  The coil body 270 includes a rectangular flat plate-like base material 271 made of glass epoxy and a spiral conductive portion 272 formed on the base material 271. A conductive line (not shown) is electrically connected to the first end portion 273 on the inner peripheral side and the second end portion 274 on the outer peripheral side of the spiral conductive portion 272. As a result, the power received by the power receiving antenna 201 can be guided to the rectifying unit 202. Such a coil body 270 is placed on the rectangular bottom plate portion 216 of the case body 260 and fixed on the bottom plate portion 216 by an appropriate fixing means.

On the coil body 270, the ferrite base material 28 is separated from the coil body 270 by the first distance d _1.
0 is arranged. As the ferrite base material 280, one having a large specific resistance, a large magnetic permeability, and a small magnetic hysteresis is desirable. The ferrite base material 280 is arranged with a space of the first distance d ₁ above the coil body 270 by being fixed to the case body 260 by an appropriate means. With such a layout, the lines of magnetic force generated on the power transmission antenna 105 side have a high rate of transmission through the ferrite base material 280, and in power transmission from the power transmission antenna 105 to the power reception antenna 201, the metal lines constituting the vehicle main body are used. The effect on the magnetic field lines is minimal.

In addition, in the upper opening 263 of the case body 260, a rectangular flat aluminum substrate 290 that covers the upper opening 263 is disposed above the ferrite substrate 280 with a second distance d _2. It is like that. As a metal material used for such an aluminum base material 290, a metal other than aluminum can be used.

  In the present embodiment, the aluminum base material 290 is arranged so as to cover the upper opening 263, so that the influence of the vehicle body metal part on the coil body 270 can be suppressed. It is possible to determine the characteristics of According to the present embodiment, since the characteristics of the antenna are fixed, it is possible to expect the same power transmission characteristics regardless of the vehicle type to which the receiving antenna 201 is attached, and the versatility as an antenna is expanded. Become.

In the present embodiment, the power receiving antenna 201 is attached to the vehicle main body using the vehicle body attachment 265 in the upper opening 263. As the structure of the vehicle body attachment portion 265, a conventionally known one can be used as appropriate. A flange member or the like may be provided around the upper opening 263 in order to improve attachment to the vehicle main body.

As described above, the antenna of the present invention includes the coil body 270 in which the predetermined conductive portion 272 is formed on the insulating base material 271 having the main surface, and the coil body 270 and the first distance d on the coil body 270. ₁ spaced by a ferrite substrate 280 which is arranged, an aluminum substrate 290 which is disposed between the ferrite substrate 280 is the second distance d ₂ apart on a ferrite substrate 280, it is disposed on the aluminum substrate 290 A vehicle body attachment portion 265.

Here, the reason why the antenna of the present invention is configured as described above will be described. FIG. 5 is a diagram showing power transmission efficiency data of the present invention and a comparative example, and FIG. 6 is a diagram for explaining conditions in data acquisition.
As shown in FIG. 6 (A), the data shown in FIG. 5 (A) is obtained by using the structure according to the present invention as a power transmission antenna and a power reception antenna. The distance D between the two is acquired while being displaced.

  On the other hand, as shown in FIG. 6 (B), the data shown in FIG. 5 (B) is an iron plate that simulates a vehicle using a configuration according to a comparative example in which an aluminum base material is omitted as a power transmitting antenna and a power receiving antenna. The distance D between the power receiving side coil body and the power receiving side coil body is obtained while being displaced.

  The efficiency data according to the present invention maintains almost the same transmission efficiency regardless of the distance D, whereas the efficiency data according to the comparative example is obtained when an antenna is mounted on an actual vehicle. It can be seen that the transmission efficiency decreases when the distance D, which is likely to be used, is about 100 or less.

As described above, the antenna according to the present invention includes the ferrite base material 280 disposed on the coil body 270 and spaced apart from the coil body 270 by the first distance d ₁ , and the ferrite base material 280 and the second base material on the ferrite base material 280. And an aluminum base material 290 that is spaced apart by a distance d _2, so that even when an antenna is mounted on the bottom surface of the vehicle, the influence of metal objects constituting the vehicle main body portion is suppressed and efficiently Power transmission can be performed.

  Next, another embodiment of the present invention will be described. FIG. 7 is an exploded perspective view of a power receiving antenna 201 according to the second embodiment of the present invention, and FIG. 8 is a schematic cross-sectional view showing a state of power transmission by the power receiving antenna 201 according to the second embodiment of the present invention. . In addition, the same reference number is attached | subjected about the structure similar to previous embodiment.

  In the second embodiment, the same configuration as that of the previous embodiment is used. However, when the projection is performed in the direction perpendicular to the main surface of the base material 271, as shown in FIG. The projection formed by the coil pattern conductive portion 272 of the body 270 is included in the projection formed by the ferrite base 280, and the projection formed by the ferrite base 280 is included in the projection formed by the aluminum base 290. It is characterized by being set to be.

Here, the merit of the dimensional relationship as described above will be described. Factors that reduce the efficiency of the antenna include iron loss (eddy current loss) and copper loss (resistance loss). The iron loss is large in the order of iron (vehicle)>aluminum> ferrite, and it is desirable to minimize the loss due to iron. Therefore, the flow of magnetic flux is controlled by the ferrite base material 280 that is a magnetic body (formation of a magnetic flux path), the magnetic flux leaking to the vehicle body is reduced, and the leakage of magnetic flux that cannot be prevented by the ferrite base material 280 alone is prevented. By preventing this, the magnetic flux leaking to the car body is reduced. For this reason, as described above, the leakage of magnetic flux can be reduced by increasing the projected area in the order of the coil pattern conductive portion 272 of the coil body 270 → the ferrite base material 280 → the aluminum base material 290 → the metal portion of the vehicle. Prevent decline.

  In the embodiment as described above, the same effects as those in the previous embodiment can be obtained.

Next, it is more preferable to set how the first distance d ₁ between the coil body 270 and the ferrite base material 280 and the second distance d ₂ between the ferrite base material 280 and the aluminum base material 290 are set. A description will be given of whether an antenna can be configured.

  FIG. 9 is a diagram showing power transmission efficiency data of the present invention and a comparative example, and FIG. 10 is a diagram for explaining conditions in data acquisition.

As shown in FIG. 10, the data shown in FIG. 9 uses the configuration according to the present invention as a power transmitting antenna and a power receiving antenna, and on the power receiving side, an iron plate simulating a vehicle is arranged, and the iron plate, ferrite base material, coil body Is obtained by displacing the aluminum base material (that is, changing the second distance d ₂ ) in both the power transmitting antenna and the power receiving antenna after being fixed.

As can be seen from FIG. 9, the first distance d ₁ between the coil body 270 and the ferrite base material 280 is longer than the second distance d ₂ between the ferrite base material 280 and the aluminum base material 290. However, since transmission efficiency is improved, in the present invention, (first distance d ₁ )> (second distance d ₂ ) is set.

In both of the first embodiment and the second embodiment, it is possible to set (first distance d ₁ )> (second distance d ₂ ), thereby increasing transmission efficiency.

  Hereinafter, more preferable setting examples will be described in carrying out the first embodiment and the second embodiment.

  First, the thickness of the ferrite base material 280 is desirably set so that the amount of magnetic flux passing through the ferrite base material 280 is equal to or less than the saturation magnetic flux. Thereby, the magnetic flux which leaks to the aluminum base material 290 side can be reduced, and transmission efficiency can be raised.

  Moreover, it is desirable that the thickness of the aluminum base material 290 be a thickness that blocks the magnetic flux leaking from the ferrite base material 280. Thereby, the magnetic flux which leaks to the metal which comprises a vehicle can be reduced, and transmission efficiency can be raised.

FIG. 11 is a diagram showing the relationship between the impedance of the antenna and the transmission efficiency. According to this, it can be seen that it is desirable to adopt a configuration with a small impedance change rate as the antenna. According to the experiments by the inventors, by setting the first distance d ₁ between the coil body 270 and the ferrite base material 280 to be 9 mm or more, the impedance change is within 5Ω, and the influence on the efficiency reduction is It was found to be 10% or less.

  As described above, the antenna according to the present invention includes a ferrite base material disposed on the coil body and spaced apart from the coil body by the first distance, and an aluminum base disposed on the ferrite base material and spaced apart from the ferrite base material by the second distance. Therefore, even when the antenna is mounted on the bottom surface of the vehicle, it is possible to suppress the influence of a metal object constituting the vehicle main body and efficiently perform power transmission.

DESCRIPTION OF SYMBOLS 100 ... Power transmission system 101 ... AC / DC conversion part 102 ... Voltage adjustment part 103 ... Inverter part 104 ... Matching device 105 ... Power transmission antenna 110 ... Main control part 120- ..Communication unit 201 ... Receiving antenna 202 ... Rectification unit 203 ... Charge control unit 204 ... Battery 210 ... Main control unit 220 ... Communication unit 230 ... Interface unit 260 ... Case body 216 ... Bottom plate portion 262 ... Side plate portion 263 ... (Upper) opening 265 ... Car body mounting portion 270 ... Coil body 271 ... Base material 272 ... Conductive portion 273 ... first end 274 ... second end 280 ... ferrite substrate 290 ... aluminum substrate

Claims (4)

A coil body in which a predetermined coil pattern conductive portion is formed on an insulating substrate having a main surface;
A ferrite substrate disposed on the coil body and spaced apart from the coil body by a first distance;
Have a, an aluminum substrate that is disposed the ferrite substrate and being a second distance apart on the ferrite substrate,
The antenna according to claim 1, wherein the first distance is longer than the second distance . When projecting in a direction perpendicular to the main surface,
The projection formed by the coil pattern conductive portion is included in the projection formed by the ferrite base material,
The antenna according to claim 1, wherein the projection formed by the ferrite base material is included in the projection formed by the aluminum base material. The antenna according to claim 1 or 2 , wherein the thickness of the ferrite base is set so that the amount of magnetic flux passing through the ferrite base is equal to or less than a saturation magnetic flux. The antenna according to any one of claims 1 to 3 , wherein the aluminum substrate has a thickness that blocks magnetic flux leaking from the ferrite substrate.

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