JP2016051793A - Power transmission device and transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power transmission device in which variation of coupling coefficient is suppressed, even if the position of a power reception coil varies for a power transmission coil.SOLUTION: A power transmission device has a transmission coil, a transmission device including an AC power supply for supplying AC power to a resonance element including the transmission coil, a power reception coil for receiving power in non-contact by magnetic field coupling, a transmission device including a rectifier circuit for rectifying an AC power induced in the resonance element including the power reception coil. The transmission coil includes a first planar coil pattern having a first region where a forward transmission line and a reverse transmission line are arranged alternately in the central part, and a second region surrounding the first region where a forward line for electrical connection with the forward line in the first region is provided, and the power reception coil includes a planar second coil pattern arranged oppositely to the first region.SELECTED DRAWING: Figure 3

Description

  Embodiments described herein relate generally to a power transmission device and a coil device that transmit power from a power transmission device to a power reception device in a contactless manner.

  In recent years, devices that transmit power in a non-contact manner have become widespread. The non-contact power transmission device includes a power transmission device that transmits power and a power reception device that receives the transmitted power. As a method for transmitting power from a power transmitting device to a power receiving device in a contactless manner, an electromagnetic induction method, a magnetic field resonance method, an electric field coupling method, or the like is known. The power receiving device includes a drive circuit for driving the device itself and a load circuit such as a charging circuit for a secondary battery mounted on the power receiving device.

  In general, when using electromagnetic induction method or electric field coupling method to transmit power to electronic devices such as mobile terminals and laptop computers connected to the power receiving device, the power transmission device and the power receiving device are transmitted. It is necessary to make close contact within the possible area. On the other hand, when the magnetic field resonance method is used, it is not necessary to bring the power transmission device and the power reception device into close contact with each other. Therefore, the magnetic field resonance method has attracted attention in that it has a degree of freedom in the position where the power receiving device is placed and is excellent in usability.

  In the magnetic field resonance method, a power transmission side resonance element (also referred to as a resonance element) including a coil and a capacitor provided in a power transmission apparatus and a power reception side resonance element including a coil and a capacitor provided in the power reception apparatus are electrically coupled. Thus, power can be transmitted. Even in the electromagnetic induction system, not only the coupling of the coil on the power transmission side and the coil on the power reception side, but also a capacitor for resonance on both the power transmission side and the power reception side, and resonance coupling the elements on the power transmission side and the power reception side, Attempts have also been made to extend the distance for transmitting power. As a result, the distinction between the magnetic field resonance method and the electromagnetic induction method has disappeared.

  As a parameter that affects the efficiency of transmitting power without contact (power transmission efficiency), there is a coupling coefficient k between the resonant elements of the power transmission apparatus and the power reception apparatus. When the distance between the resonant elements of the power transmission device and the power reception device varies, the coupling coefficient k usually varies. For example, the coupling coefficient k decreases as the distance between the resonant elements increases. If the impedance of the circuit is fixed, the power transmission efficiency and the power that can be transmitted change as the coupling coefficient k changes.

  As a method for maintaining high power transmission efficiency even when the coupling coefficient k changes with a change in the distance between the resonant elements of the power transmitting device and the power receiving device, an impedance adjusting means capable of varying the impedance is provided, and the coupling coefficient k is changed. A technique for changing the impedance of a power transmission device or a power reception device according to the above is known (see Patent Document 1). The technique disclosed in Patent Document 1 has a problem that a circuit for automatically performing impedance control when the coupling coefficient k changes is necessary, and the control becomes complicated.

  A non-contact charging device using a large-diameter coil as a power transmission coil and a small-diameter coil as a power transmission coil is known as a device that can transmit power even if the positions of the power transmission coil and the power reception coil are slightly shifted. (See Patent Document 2). In the technique disclosed in Patent Document 2, when the power receiving coil is displaced in the vertical direction with respect to the power transmitting coil and the distance between the power transmitting coil and the power receiving coil is increased, the coupling coefficient k is rapidly decreased. Since the coupling coefficient k is reduced, there is a problem that power transmission efficiency is deteriorated and desired power cannot be sent.

JP 2011-50140 A JP 2008-301553 A

An object of the present invention is to provide a non-contact power transmission device and a power transmission device in which the fluctuation of the coupling coefficient k is suppressed even when the position of the power reception coil varies with respect to the power transmission coil.

In order to solve the above problems, a power transmission device according to an embodiment includes a power transmission coil, and a power transmission device including an AC power source that supplies AC power to a resonance element including the power transmission coil.
A power receiving coil that receives power in a contactless manner by magnetic field coupling, and a power transmission device that includes a rectifier circuit that rectifies AC power induced in a resonant element including the power receiving coil,
One of the power transmission coil or the power reception coil surrounds the first region in which a forward transmission line and a reverse transmission line are alternately arranged in the center, and the forward line of the first region. A first planar coil pattern having a second region provided with a forward line electrically connected to
The other of the power transmission coil or the power reception coil includes a planar second coil pattern arranged to face the first region.

The circuit block diagram which shows the structure of the electric power transmission apparatus which concerns on 1st Embodiment. The perspective view which shows the structure of the electric power transmission apparatus which concerns on 1st Embodiment. The perspective view which shows roughly the coil apparatus containing the power transmission coil and power receiving coil in 1st Embodiment. The top view which shows an example of the shape and dimension of the coil apparatus in 1st Embodiment. Sectional drawing which shows the positional relationship of the power transmission apparatus and power receiving apparatus in 1st Embodiment. Sectional drawing which shows the other positional relationship of the power transmission apparatus and power receiving apparatus in 1st Embodiment. The top view which shows the power transmission coil of a common electric power transmission apparatus. Explanatory drawing which shows the measurement system of the coupling coefficient k in the electric power transmission apparatus which concerns on 1st Embodiment. The characteristic view which shows the relationship between the distance between transmission / reception coils in 1st Embodiment, and the coupling coefficient k. Sectional drawing which shows the positional relationship of the coil pattern of a general power transmission coil and a receiving coil. Sectional drawing which shows the positional relationship of the coil pattern of the power transmission coil and power receiving coil in 1st Embodiment. The top view which shows the state which moved the receiving coil horizontally in 1st Embodiment. The characteristic view which shows the relationship between the deviation | shift amount of the horizontal direction in 1st Embodiment, and the coupling coefficient k. The top view which shows an example of the coil pattern in 1st Embodiment. The top view which shows an example of the coil pattern in 1st Embodiment. The top view which shows an example of the coil pattern in 1st Embodiment. The top view which shows an example of the coil pattern in 1st Embodiment. The top view which shows an example of the coil pattern in 1st Embodiment. The top view which shows an example of the coil pattern in 1st Embodiment. The perspective view which shows the structure of the electric power transmission apparatus which concerns on 2nd Embodiment.

  Embodiments for carrying out the invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected about the same location.

  (First embodiment)

  FIG. 1 is a circuit block diagram showing the overall configuration of the power transmission device according to the first embodiment. FIG. 2 is a perspective view schematically showing a power transmission device and a power reception device that constitute the power transmission device. As illustrated in FIG. 1, the power transmission device includes a power transmission device 10 that transmits power and a power reception device 20 that receives the power transmitted from the power transmission device 10. The power transmitting device 10 and the power receiving device 20 transmit power by a method using electromagnetic coupling such as a magnetic field resonance method or an electromagnetic induction method. Hereinafter, the case where electric power is transmitted by the magnetic field resonance method or the electromagnetic induction method will be described.

  The power transmission device 10 includes an AC power supply 11 that generates electric power, and a resonance element 14 including a resonance capacitor 12 and a power transmission coil 13. The AC power supply 11 generates AC power having the same or substantially the same frequency as the self-resonant frequency of the power transmission resonance element 14 and supplies the AC power to the resonance element 14. Specifically, the AC power supply 11 includes an oscillation circuit that generates 6.78 MHz AC power and a power amplification circuit that amplifies the output of the oscillation circuit. DC power is supplied from an AC adapter provided outside the power transmission apparatus 10 to the AC power supply 11 in the power transmission apparatus 10, so that an oscillation circuit and a power amplification circuit in the AC power supply 11 operate.

  The AC power supply 11 can be a switching power supply instead of the AC power supply 11 including the oscillation circuit and the power amplification circuit. The AC power supply 11 composed of a switching power supply is configured to turn on / off the switching element by the output of the oscillation circuit. The resonant element 14 is operated by turning on / off the switching element.

  Instead of providing an AC adapter outside and supplying DC power to the AC power supply 11, an AC adapter or an AC / DC conversion unit may be provided in the power transmission device 10. AC 100 V is supplied from the outside to the power transmission device 10, and DC power generated by an AC adapter or an AC / DC conversion unit in the power transmission device 10 is supplied to the AC power source 11. In this case, the resonant element 14 is operated by the AC power supply 11.

  Although the operating frequency is exemplified as 6.78 MHz, the operating frequency can be changed as necessary. Other operating frequencies such as 13.56 MHz and 27.12 MHz are used.

  The power reception device 20 includes a resonance element 23 including a resonance capacitor 21 and a power reception coil 22, a rectifier circuit 24 that converts alternating current into direct current, and a load circuit 25. The self-resonant frequency of the power-receiving resonant element 23 is the same as or substantially the same as the self-resonant frequency of the power-transmitting resonant element 14, and the power is efficiently transmitted from the power-transmitting side to the power-receiving side.

  The load circuit 25 is a circuit of an electronic device such as a mobile terminal or a tablet terminal. The power received by the power receiving device 20 is used for operations of the electronic device, charging of a battery built in the electronic device, and the like. In general, the load circuit 25 operates with DC power. In order to supply DC power to the load circuit 25, the power receiving device 20 is provided with a rectifier circuit 24 that rectifies AC power induced in the power receiving resonance element 23 and converts it into DC power. In FIG. 1, the power receiving device 20 includes a load circuit 25. However, the power receiving device 20 is not necessarily limited to the configuration including the load circuit 25, and the load circuit 25 is provided outside the power receiving device 20, and the DC power generated by the rectifier circuit 24 is supplied to the load circuit 25. It is also possible to make it.

  In the power transmission device 10 and the power reception device 20, the resonance capacitors 12 and 21 are not necessarily configured by electronic components. The capacitance corresponding to the resonance capacitors 12 and 21 can be substituted by the capacitance between the coil wires depending on the shape of the coil and the inductance value of the coil. Further, the resonance capacitor 12 and the power transmission coil 13 are connected in series, and the resonance capacitor 21 and the power reception coil 22 constitute a series resonance circuit. Instead of the series resonance circuit, each resonance capacitor and coil may be connected in parallel to form a parallel resonance circuit.

  In the power transmission device of FIG. 1, as illustrated in FIG. 2, power is transmitted to the power receiving device 20 by superimposing the power receiving coil 22 on the power transmitting coil 13 of the power transmitting device 10. That is, a magnetic field is generated in the power transmission coil 13 by passing an alternating current through the power transmission coil 13. On the other hand, an alternating current flows through the power receiving coil 22 due to magnetic field coupling, and electric power can be obtained by rectifying the current.

  As illustrated in FIG. 2, the casing 15 of the power transmission device 10 has a plane on which the power reception device 20 can be placed. The power transmission device 10 has a configuration in which the power transmission coil 13 is disposed in the lower plane of the housing 15. The housing 26 of the power receiving device 20 has a flat surface that can be placed on the flat surface of the power transmitting device 10. When the power reception device 20 is placed on the power transmission device 10, the power reception coil 22 is disposed in the housing 26 so that the power reception coil 22 faces the power transmission coil 13.

  FIG. 3 is a perspective view schematically showing a coil device for power transmission including the power transmission coil 13 and the power reception coil 22. In order to facilitate understanding of the positional relationship and configuration of the power transmission coil 13 and the power reception coil 22, only the power transmission coil 13 and the power reception coil 22 are illustrated except for the housing 15 and the housing 26.

  The power transmission coil 13 is composed of a rectangular coil pattern 131 (first coil pattern) formed on the printed circuit board 17. As the printed board 17, a glass epoxy (FR-4) board having a 35 μm thick copper foil is used. The copper foil was etched into a desired shape shown in the figure to form a coil pattern for the power transmission coil 13.

  Magnetic flux is generated by passing a current between two points A11 (coil pattern start end) and A12 (coil pattern end) of the coil pattern for the power transmission coil 13. In a region 18 (region surrounded by W13 and L13 shown in FIG. 4) at the center of the coil pattern, a forward wiring pattern and a reverse wiring pattern are formed. A coil pattern heading from the coil pattern start end A11 toward the center along the winding pattern wired along the outer periphery of the printed circuit board 17 is called a forward wiring pattern. In contrast to the forward wiring pattern, the reverse wiring pattern represents a pattern wound from the coil central portion toward the outer peripheral portion. That is, as shown in FIG. 3, when a current flows in the CW direction (clockwise direction of rotation of the watch hands) along the forward wiring pattern, a current flows in the CCW direction (counterclockwise) in the reverse wiring pattern. become. A reverse wiring pattern is a wiring pattern that is not only from the center to the outer periphery but also flows in the opposite direction to the current flowing through the forward wiring pattern and is provided close to the forward wiring pattern. It functions to cancel the magnetic flux generated by the magnetic flux generated by the reverse wiring pattern.

  The region 18 at the center of the power transmission coil 13 has a configuration in which the wiring of the reverse wiring pattern is arranged between two wirings of the forward wiring pattern. In FIG. 3, the forward wiring pattern for three turns is arranged between the backward wiring patterns for three turns. In the central region 18, the forward wiring pattern and the reverse wiring pattern enter each other to generate a combined magnetic flux that generates two patterns. That is, in the region 18, the magnetic flux generated from the current flowing in the forward direction and the magnetic flux generated from the current flowing in the reverse direction are combined, and the magnetic fluxes cancel each other.

  In the central region 18 where the magnetic flux is cancelled, the magnetic flux generated from the power transmission coil 13 is reduced, so that the coupling by the magnetic flux with the power receiving coil 22 is reduced. A coil pattern 131 of the power transmission coil 13 surrounds the region 18 and is configured by a 6-turn flat pattern. The coil pattern 131 formed outside the region 18 is a forward wiring pattern. The magnetic flux generated by the coil pattern 131 formed on the outer side is coupled with the power receiving coil by the magnetic flux without being affected by the reverse wiring pattern. Therefore, the magnetic flux generated by the coil pattern 131 formed on the outside is strongly coupled to the power receiving coil 22 as compared with the magnetic flux generated in the central region 18 where the magnetic flux is canceled.

  The power receiving coil 22 includes a rectangular coil pattern 221 formed on the printed circuit board 27. As the printed board 27, a glass epoxy (FR-4) board having a 35 μm thick copper foil is used. The copper foil was etched into the desired shape shown in the figure to form a coil pattern for the receiving coil 22. The power receiving coil 22 has 6 turns in a forward wiring pattern. The outer shape of the power reception coil 22 is slightly smaller than the size of the central region 18 of the power transmission coil 13.

  The power transmission coil 13 and the power reception coil 22 may be formed on a PET (polyethylene terephthalate) flexible substrate instead of a coil pattern formed by patterning a copper foil on a glass / epoxy printed circuit board. Moreover, it may replace with copper foil and may make it form a planar coil by winding a copper wire or a litz wire.

  FIG. 4 is a plan view showing a specific shape of the coil device according to the first embodiment. As shown in FIG. 4A, the power transmission coil 13 is formed by a coil pattern 131 from a start point A11 to an end point A12 formed on the printed circuit board 17. The outer shape of the power transmission coil 13 is a square of L11 = W11 = 153 mm. From the starting point A11 to the starting point A13 of the central region 18, a forward wiring coil pattern of about 6 turns is formed surrounding the region 18. The width D11 of the forward wiring coil pattern surrounding this region 18 is 3 mm, and the gap E11 between adjacent coil patterns is 3 mm.

  In the central region 18, the forward wiring coil pattern is formed with about 3 turns from the point A13 to the center point A14, the pattern width D13 is 3 mm, and the gap E13 between adjacent coil patterns is 3 mm. In the central region 18, the reverse wiring coil pattern folded back at the center point A 14 is formed with about 4 turns from the center point A 14 to the end point A 12, the pattern width D 12 is 3 mm, and the gap E 12 between adjacent coil patterns is 3 mm. Has been. The inductance value of the formed power transmission coil 13 is about 8.37 μH.

  In the central region 18, the forward wiring coil pattern from the point A13 to the central point A14 is continuously connected to the reverse wiring coil pattern at the center point A14. The forward wiring coil patterns A13 to A14 are arranged between the wirings of the reverse wiring coil patterns A14 to A12. In FIG. 4, the forward wiring coil pattern and the reverse wiring coil pattern are alternately arranged in a substantially parallel linear pattern except for corners. By arranging the forward wiring coil pattern and the backward wiring coil pattern in parallel, the generation of magnetic flux is suppressed in the substantially square central region 18 as compared with the configuration in which the forward wiring coil pattern and the reverse wiring coil pattern are arranged non-parallel. it can.

In the region 18 at the center of the power transmission coil 13, the forward wiring coil has W12 = L12 = 69 mm. The coil area of the forward wiring is L12 × W12 = 4761 mm ² . The coil of the reverse wiring is W13 = L13 = 81.5 mm. The coil area of the reverse wiring is L13 × W13 = 6642.25 mm ² . The outer area of the power transmission coil 13 is L11 × W11 = 153 × 153 = 23409 mm ² , and the ratio of the area 18 to the outer area of the power transmission coil 13 is 664.25 / 23409 × 100 = 28.37% ( ≒ 30%).

FIG. 4B is a diagram illustrating a specific shape of the power receiving coil 22. The power receiving coil 22 has a coil pattern 221 formed on the printed circuit board 27, and the power receiving coil 22 has an outer shape of a square of L21 = W21 = 63 mm. The coil pattern width D21 is 3 mm, the gap E21 between adjacent coil patterns is 2 mm, and it has a shape wound about 6 turns. The inductance value is about 1.28 μH. The area of the power reception coil 22 is L21 × W21 = 63 × 63 = 3969 mm ² , which is smaller than the area of the region 18 of the power transmission coil 13.

  An operation of the power transmission device according to the first embodiment will be described.

  FIG. 5 is a cross-sectional view of the power transmission device 10 and the power reception device 20. FIG. 5A shows a state in which the housing 26 of the power receiving device 20 is spaced apart from the upper portion of the housing 15 of the power transmitting device 10. FIG. 5B shows a state in which the housing 26 of the power receiving device 20 is disposed in contact with the housing 15 of the power transmitting device 10, and the distance between the power transmitting coil 13 and the power receiving coil 22 is the smallest and close to each other. State. The power transmission coil 13 is provided along the upper surface in the housing 15, and the power receiving coil 22 is provided along the lower surface in the housing 26. In order to efficiently transmit power from the power transmitting coil 13 to the power receiving coil 22 in a non-contact manner, it is desirable that the power transmitting coil 13 and the power receiving coil 22 be arranged as close as possible.

  FIG. 6 is another cross-sectional view of the power transmission device 10 and the power reception device 20. FIG. 6A shows a case where the casing 26 of the power receiving device 20 is put in the cover 262 for the purpose of protection or the like. The distance between the power transmission coil 13 and the power reception coil 22 is increased by the thickness of the cover 262 with respect to FIG. The thickness of the cover 262 is about 5 mm, assuming that the power receiving device 20 is a mobile terminal, a tablet terminal, or the like. FIG. 6B assumes a case where a portable terminal, a tablet terminal, or the like is carried in a bag 264 and placed in the case 15 of the power transmission apparatus 10 while being charged in the bag 264. The distance between the power transmission coil 13 and the power reception coil 22 is increased by the thickness of the cover 262 and the collar 264. Compared to FIG. 5B, it is assumed that the distance increases by about 10 mm to 20 mm.

  FIG. 7 shows a power transmission coil 41 having a conventional coil pattern 411 composed of only a forward wiring coil pattern. In other words, the coil pattern 411 has no combination of the reverse wiring coil pattern and the forward wiring coil pattern in the region 18 shown in FIG. The outer size is L41 = W41 = 153 mm, which is the same as that of the power transmission coil 13 of the first embodiment.

  In the coil pattern 411 composed of only the forward wiring coil pattern, the coupling coefficient k changes greatly even if the distance between the power transmission coil and the power reception coil changes by several mm. In order to reduce the change in the coupling coefficient k, it is necessary to control the impedances of the power transmission coil and the power reception coil. In a situation where the impedance is not controlled, the amount of electric power that can be received at a certain distance is maximized, and the amount of electric power that can be received even if the distance is greater than or less than that distance decreases.

  In the case where the power transmission coil 13 and the power reception coil 22 shown in FIG. 4 are combined, and in the case where the power transmission coil 41 and the power reception coil 22 shown in FIG. Compare how it changes. The distance between the coils indicates the distance to the power receiving coil 22 in the normal direction of the power transmitting coil 13 when the planar power transmitting coil 13 and the planar power receiving coil 22 are arranged in parallel.

The coupling coefficient k can be obtained from Equation (1) by actually measuring the self-inductance Lopen and the leakage inductance Lsc.

  FIG. 8 is a diagram illustrating a measurement system for the coupling coefficient k in the power transmission device. As shown in FIG. 8, one coil 51 is connected to a measuring instrument 53 (LCR meter), and both ends 54 and 55 of the other coil 52 are opened, and the self-inductance Lopen and both ends 54 and 55 are short-circuited. The leakage inductance Lsc is measured by the measuring device 53. Using the leakage inductance Lsc and the self-inductance Lopen, the coupling coefficient k is obtained by Equation (1).

  FIG. 9 is a diagram showing the characteristics of the coupling coefficient k when the distance between the power transmission coil and the power reception coil (distance between the transmission and reception coils) is changed. The horizontal axis represents the distance (mm) between the power transmitting and receiving coils, and the vertical axis represents the coupling coefficient k. A solid line C in FIG. 9 indicates characteristics when the power transmission coil 13 and the power reception coil 22 of the first embodiment are used, and a broken line D indicates characteristics when the power transmission coil 41 and the power reception coil 22 of FIG. 7 are used. Show. In the case of using the power transmission coil 13 of the first embodiment, the coupling coefficient k gradually decreases when the distance between the power transmission coil 13 and the power reception coil 22 (distance between the transmission and reception coils) is changed from 2 mm to 60 mm. On the other hand, when the power transmission coil 41 is used, the rate of change of the coupling coefficient k increases as the distance between the power transmission coil 41 and the power receiving coil 22 becomes shorter than 30 mm, and the change of the coupling coefficient k increases as the distance from the 30 mm increases. Has become moderate. It can also be seen that when the distance between the transmission and reception coils is about 30 mm to 60 mm, the coupling coefficient k between the power transmission coil 41 and the power reception coil 22 approaches the coupling coefficient k in the case of the first embodiment.

  As shown in FIGS. 5 and 6, the distance between the transmitting and receiving coils is often about 20 mm or less when used for actual device charging. When the change rate of the coupling coefficient k when the distance between the transmitting and receiving coils is changed from 2 mm to 20 mm is calculated, in the first embodiment (solid line C), 0.161 / 0.205 = 0.785. That is, the value of the coupling coefficient k when the distance between the transmitting and receiving coils is 20 mm is about 80% of the value when the distance between the transmitting and receiving coils is 2 mm. On the other hand, when the change rate of the coupling coefficient k when the distance between the transmitting and receiving coils is changed from 2 mm to 20 mm on the broken line D is 0.251 / 0.486 = 0.516, the distance between the transmitting and receiving coils is 20 mm. In this case, the value of the coupling coefficient k is reduced to about 50% of the value when the distance between the transmitting and receiving coils is 2 mm.

  As described above, by using the power transmission coil 13 of the first embodiment, the change in the coupling coefficient k can be moderated with respect to the change in the distance between the transmission and reception coils. As a result, changes in the amount of power that can be received and the power transmission efficiency can be suppressed, and complicated control such as impedance control can be eliminated.

  With reference to FIGS. 10 and 11, how the coupling coefficient k changes will be schematically described. FIG. 10 shows a case where the power transmission coil 41 (FIG. 7) and the power reception coil 221 formed only by the forward wiring coil pattern 411 are used, and FIG. 11 shows the power transmission coil 13 and the power reception coil according to the first embodiment. The case where 221 is used is shown.

  Consider the case where the power transmission coil 41 of FIG. 10 is used. When the power transmission coil 41 and the power reception coil 22 are close to each other as shown in FIG. 10A, the power transmission coil pattern 411 and the power reception coil 221 are strongly coupled to each other, so that the coupling coefficient k is a high value. Become. In FIG. 10, an oval portion surrounded by a dotted line schematically shows how the coils are electromagnetically coupled. When the power transmission coil 41 and the power reception coil 22 are separated as shown in FIG. 10B, the coupling coefficient k becomes weaker than that in the case of FIG. 10A and decreases according to the distance (see FIG. 9). . In particular, as shown in (a), in a situation where the coils are strongly coupled to each other, the coupling coefficient k tends to change greatly only by slightly changing the distance between the transmitting and receiving coils.

  Next, with reference to FIG. 11, the case where the power transmission coil 13 and the power reception coil 22 are used is demonstrated. FIG. 11A shows a situation where the power transmission coil 13 and the power reception coil 22 are arranged close to each other, and FIG. 11B shows a situation where the power transmission coil 13 and the power reception coil 22 are separated from each other as compared to FIG. Is shown. 11 (a) and 11 (b), the power receiving coil 22 is opposed to a region 18 composed of a forward wiring pattern and a reverse wiring pattern of the power transmission coil 13. When placed close to each other as shown in FIG. 11 (a), the coil pattern 131 and the coil pattern 221 are joined mainly at the edge of the coil, as shown by the broken line ellipse. As a result, even when the coils are close to each other, the coupling coefficient k does not become a large value. As shown in FIG. 11B, when the power transmitting coil 13 and the power receiving coil 22 are separated from each other, as shown by a broken line ellipse, they are coupled at the edge of the coil, but the area of the coil pattern contributing to the coupling is qualitative. Therefore, the area of the coil pattern contributing to the coupling in FIG. That is, the decrease in the coupling due to the separation of the distance between the coils is compensated to some extent by increasing the area of the coil pattern contributing to the coupling. As a result, the coupling coefficient k tends to decrease as the distance between the transmitting and receiving coils increases, but the change becomes gentle as shown by the solid line C in FIG.

  The case where the distance to the power receiving coil 22 in the normal direction of the planar power transmitting coil 13 has been described above. In a power transmission coil having a combination of a forward wiring coil pattern and a reverse wiring coil pattern in the central region, even if the position of the power reception coil 22 changes along the plane of the power transmission coil 13, the change in the coupling coefficient k is reduced. Can do.

  As described above, when the power receiving coil pattern 221 is placed in proximity to the power transmitting coil pattern 131, it is coupled mainly at the edge of the coil, as indicated by the dashed ellipse. If the coil pattern 221 is too large compared to the central region 18, the coupling at the coil edge becomes too strong. If the coupling at the coil edge is too strong, when the power transmitting coil and the power receiving coil are separated from each other, a change in the coupling coefficient k tends to increase. Therefore, the outer shape of the power reception coil 22 is slightly smaller than the size of the central region 18 of the power transmission coil 13.

  FIG. 12 shows a state where the power receiving coil 22 is moved by a distance δ in the direction of the arrow X along the plane of the power transmitting coil 13 by the combination of the power receiving coil 22 and the power transmitting coil 13 shown in FIG. A solid line C in FIG. 13 shows a change characteristic of the coupling coefficient k when the power receiving coil 22 is moved in the arrow X direction. For comparison, a broken line D in FIG. 13 shows a time when the power receiving coil 22 is moved in the arrow X direction using the power transmitting coil 41 (see FIG. 7) and the power receiving coil 22 formed only by the forward wiring coil pattern 411. The change characteristic of the coupling coefficient k is shown. The coil 41 has about 13 turns and an inductance value of about 15.335 μH.

  In FIG. 13, the amount by which the power receiving coil 22 is moved along the power transmitting coil 13 is described as a horizontal shift amount (δ). The horizontal axis represents the horizontal displacement (δmm), and the vertical axis represents the coupling coefficient k. In the broken line D, as the horizontal shift amount of the power receiving coil 22 increases from the center of the power transmitting coil 41, the area where the power transmitting coil 41 and the power receiving coil 22 face each other decreases, and the coupling coefficient k greatly decreases. On the other hand, in the solid line C, the coupling coefficient k hardly changes until the deviation of 40 mm, and the coupling coefficient k is slightly reduced even when the deviation is about 50 mm.

  The reason why the coupling coefficient k is small even when the power receiving coil 22 moves along the coil surface of the power transmitting coil 13 is that it is easy to be magnetically coupled to the power receiving coil 22 at the end of the central region 18 and to couple the magnetic flux. It is considered that the change in the area of the power transmitting coil 13 and the power receiving coil 22 that contributes is small. In the case of the first embodiment, the change in the coupling coefficient k can be reduced as long as the power receiving coil 22 does not protrude from the power transmitting coil 13.

  In 1st Embodiment, the power transmission coil 13 and the receiving coil 22 have shown the example of substantially square shape. The shape is not limited to a square, and may be a quadrangle such as a rectangle or a polygon (such as a hexagon or an octagon). Further, although it may be circular, a polygonal shape is preferable in consideration of an allowable amount when the power receiving coil 22 is moved along the power transmitting coil 13. Even if the power transmission coil substrate 17 is a multilayer printed circuit board, a forward pattern is wired on the first layer, and a reverse pattern is wired on the second layer corresponding to the central region of the first layer, as shown in FIG. The same effect as the coil pattern can be obtained. Of course, it is also possible to wire a reverse pattern on the first layer and a forward pattern on the second layer. Moreover, even if the power transmission coil substrate 17 is a double-sided printed circuit board, a forward pattern is wired on one surface, and a reverse pattern is wired on the other surface corresponding to the central region of the surface, as shown in FIG. The same effect as the coil pattern can be obtained.

  With reference to FIG. 14 thru | or FIG. 19, the pattern of another power transmission coil is illustrated.

  FIG. 14 shows a second power transmission coil pattern. In the second power transmission coil pattern, the forward wiring coil pattern A31-A32, the pattern between A32 and A35, the pattern between A35 and A33, and the pattern between A33 and A34 are continuous. The pattern between A32 and A35 is a forward wiring, the reverse wiring between A35 and A33, and the forward wiring between A33 and A34. A current is applied between A31 and A34 to generate an induction magnetic field. Thus, even if a plurality of forward wirings and reverse wiring patterns are mixed in the central region, the same effect can be obtained.

  FIG. 15 shows a third power transmission coil pattern. In the third power transmission coil pattern, A41 is the starting point and A48 is the ending point. A42, A43, A44, A45, A46, and A47 are turning points of the coil pattern of the forward wiring and the coil pattern of the reverse wiring. In the third power transmission coil pattern, as in the first coil pattern, the direction of the current flowing through the coil in the adjacent wiring in the central region is reversed. Therefore, even if this coil pattern wiring is used, the same effect as the first coil pattern can be obtained. Here, the locations of the turning points A42, A43, A44, A45, A46, A47 are not limited.

  FIG. 16 shows a fourth power transmission coil pattern. In the fourth power transmission coil pattern, A51 is the starting point and A66 is the ending point. The central region of the power transmission coil pattern has a pattern wired in a zigzag manner. A53-A54, A55-A56, A57-A58, A59-A60, A61-A62, A63-A64, A65-A66 are forward wiring coil patterns. A52-A53, A54-A55, A56-A57, A58-A59, A60-A61, A62-A63, A64-A65 are coil patterns of reverse wiring. In the fourth power transmission coil pattern, since the coil patterns are arranged in a zigzag manner in the central region, the direction of the current flowing through the coil in the adjacent wiring in the central region is reversed as in the first coil pattern. Therefore, even if this coil pattern wiring is used, the same effect as the first coil pattern can be obtained.

  FIG. 17 shows a fifth power transmission coil pattern. In the fifth power transmission coil pattern, A71 is the starting point and A86 is the ending point. A magnetic field is generated by energizing between A71 and A86. Similar to FIG. 16, the central region of the power transmission coil pattern has a pattern wired in a zigzag manner. A73-A74, A75-A76, A77-A78, A79-A80, A81-A82, A83-A84, A85-A86 are forward wiring coil patterns. A72-A73, A74-A75, A76-A77, A78-A79, A80-A81, A82-A83, A84-A85 are coil patterns of reverse wiring. Even in the fifth power transmission coil pattern, since the coil patterns are zigzag arranged in the central region, the direction of the current flowing through the coil in the adjacent wiring in the central region is reversed as in the first coil pattern. Therefore, even if this coil pattern wiring is used, the same effect as the first coil pattern can be obtained.

  FIG. 18 shows a sixth power transmission coil pattern. In the sixth power transmission coil pattern, A90 is the starting point and A91 is the ending point. Coil patterns are arranged in a substantially star shape in the central region. A93-A94, A95-A96, A97-A98, A99-A100, A101-A102, A103-A104, and A105-A106 are forward wiring coil patterns. A92-A93, A94-A95, A96-A97, A98-A99, A100-A101, A102-A103, A104-A105, and A106-A91 are reverse wiring coil patterns. Even if this coil pattern wiring is used, the combined magnetic flux of the forward wiring and the reverse wiring can be obtained in the central region, and the effect of suppressing the magnetic flux in the central region can be obtained in the same manner as the first coil pattern. .

    FIG. 19 shows a seventh power transmission coil pattern. In the seventh power transmission coil pattern, A110 is the starting point and A112 is the ending point. A current is supplied between A110 and A112 to generate a magnetic flux for power transmission. In the center region, coil patterns are arranged in a circle, and a forward wiring coil pattern and a reverse wiring coil pattern are formed with A111 as a boundary. Even if this coil pattern wiring is used, it can be set as the synthetic | combination magnetic flux of a forward direction wiring and a reverse direction wiring in a center area | region, and a magnetic flux suppression effect is acquired like a 1st coil pattern. The coil pattern in the central region is not limited to a circle but can be a polygon (such as a hexagon or an octagon).

  In addition, the dimension of the coil shown in 1st Embodiment was only shown as an example, and is not limited to those numerical values. The ratio of the region 18 to the entire power transmission coil is about 30%, but is not limited to 30%, and the same effect can be obtained in the range of about 30% to 70%. In addition, although the coil pattern width of the forward wiring and the reverse wiring in the region 18 is 3 mm, the coil pattern width is not limited to 3 mm. For example, the same effect can be obtained in a range of about 0.1 mm to 5 mm. Further, the gap between the coil pattern of the forward wiring and the coil pattern of the reverse wiring adjacent to each other in the region 18 has been described as 3 mm. However, the gap is not limited to 3 mm. Can get.

  (Second Embodiment)

  A second embodiment will be described with reference to FIG. In 2nd Embodiment, the power transmission coil 13 of the power transmission apparatus 10 is formed only with a forward wiring pattern, and the power reception coil 22 of the power reception apparatus 20 adds the combination of a forward wiring and a reverse wiring pattern to a forward wiring pattern. It is a configuration. In other words, the power receiving coil 22 is composed of a coil pattern 221 formed on a printed circuit board, and the central region 28 is a region composed of a forward wiring pattern and a reverse wiring pattern. In the coil pattern 221, a forward wiring pattern is formed several turns from the outer edge portion around the area 28. 20, a coil pattern similar to the power transmission coil pattern in FIGS. 4, 14 to 19 can be applied.

  The power transmission coil 13 composed of the coil pattern 131 is formed on the printed circuit board so that the outer shape is substantially equal to the size of the region 28 or smaller than the region 28. The power transmission coil 13 is provided along the upper surface in the housing 15, and the power receiving coil 22 is provided along the lower surface in the housing 26. In order to transmit electric power from the power transmission coil 13 to the power reception coil 22 in a non-contact manner, the power transmission coil 13 and the power reception coil 22 are arranged as close as possible.

  Even in the second embodiment, as shown in the first embodiment, even if the distance between the power transmission coil 13 and the power reception coil 22 varies, the coupling coefficient k is less likely to vary.

  The power receiving device 20 in the first and second embodiments can be applied to, for example, a battery device, an adapter, and a terminal body. In the case of a battery device, a coil 22 and a rectifier circuit 24 are provided in the device, and a charging circuit and a battery are provided as a load circuit 25 and integrated. The battery can be charged by placing the battery device on the charging stand (power transmission device 10). In the case of an adapter, the coil and the rectifier circuit are integrated to form an adapter, and the terminal body and the adapter are connected. Moreover, when the power receiving apparatus 20 is a terminal body, it is a case where a coil and a rectifier circuit are provided inside the terminal to be integrated with the terminal. The terminal is a mobile phone, a smartphone, a handy terminal, a mobile printer, a tablet, a notebook computer, or the like.

  According to the embodiment described above, even if the distance between the resonant elements of the power transmission device 10 and the power reception device 20 varies, the variation of the coupling coefficient k can be suppressed, impedance control is unnecessary, and the power transmission efficiency is kept high. An electric power transmission device that can be provided can be provided.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and gist of the invention.

DESCRIPTION OF SYMBOLS 10 ... Power transmission apparatus 11 ... AC power supply 13 ... Power transmission coils 131, 221 ... Coil patterns 14, 23 ... Resonance elements 15, 26 ... Case 17, 27 ... Substrate 18, 28 ... Central region 20 ... Power reception apparatus 22 ... Power reception Coil 24 ... Rectifier circuit

Claims (5)

A power transmission device including a power transmission coil and an AC power source that supplies AC power to a resonance element including the power transmission coil;
A power receiving coil that receives power in a contactless manner by magnetic field coupling, and a power transmission device that includes a rectifier circuit that rectifies AC power induced in a resonant element including the power receiving coil,
One of the power transmission coil or the power reception coil surrounds the first region in which a forward transmission line and a reverse transmission line are alternately arranged in the center, and the forward line of the first region. A first planar coil pattern having a second region provided with a forward line electrically connected to
The other of the power transmission coil or the power reception coil is a power transmission device provided with a planar second coil pattern arranged to face the first region.   The power transmission device according to claim 1, wherein the forward transmission line and the reverse transmission line provided in the first region are arranged in parallel.   The power transmission device according to claim 1 or 2, wherein a size of the second coil pattern is smaller than a size of the first region.   4. The power transmission device according to claim 1, wherein an area of the first region is 30 to 70% of an outer area of the first coil pattern. 5. A first region in which a forward transmission line and a reverse transmission line are alternately arranged in the center, and a forward line that surrounds the first region and is electrically connected to the forward line in the first region A power transmission coil comprising a planar coil pattern having a second region provided with
A power transmission device that transmits power in a contactless manner by magnetic field coupling to a power reception device having an AC power source that supplies AC power to a resonance element including the power transmission coil.

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