JP5400734B2 - Non-contact power transmission device - Google Patents

Description

  The present invention relates to a non-contact power transmission apparatus suitable for performing power transmission to different power receiving apparatuses.

  In recent years, a method for transmitting power in a contactless manner to an electronic device such as a mobile phone, a digital camera, or a laptop computer has become widespread. Such an electronic device requires a dedicated power transmission device as a charger, and is required to support a plurality of electronic devices with one power transmission device.

  In Patent Document 1, it is possible to support charging of a plurality of electronic devices with one power transmission device by setting charging conditions according to each electronic device and changing the voltage and frequency applied to the power transmission coil in the power transmission device. A method has been proposed. In addition, a method has been proposed for optimal power according to electronic equipment by selecting the diameter, coil length, number of turns, and the like of the coil wire of the power receiving coil for one charging condition. In general, since electronic devices are required to be downsized, when the required power is small, it is necessary to further reduce the outer shape of the power receiving coil.

  An example of the power transmission coil and the power reception coil is shown in FIG. FIG. 7A is a cross-sectional view of the power transmission coil and the power reception coil, and FIG. 7B is a perspective view of the power transmission coil. The power transmission coil 51 and the power reception coil 61 are arranged to face each other. The magnetic flux 71 is linked to the power transmission coil 51 and the power reception coil 61, and power is transmitted from the power transmission side to the power reception side. Magnetic sheets 53 and 63 are respectively attached to the surfaces opposite to the surfaces where the power transmission coil 51 and the power reception coil 61 are opposed to suppress unnecessary radiation.

JP 2002-44884 A

  As the power required in the electronic device is smaller, the outer shape of the power receiving coil 61 is smaller than the outer shape of the power transmitting coil 51, and the leakage magnetic flux generated from the power transmitting coil 51 is increased. Therefore, if a metal case or a metal part is disposed in the vicinity of the power receiving coil 61, heat generation or noise is caused.

  The present invention has been made in consideration of such problems, and suppresses the generation of leakage magnetic flux even when power is transmitted to power receiving coils having different external shapes, and requires different power for one power transmission device. An object of the present invention is to provide a non-contact power transmission device that can support charging of a plurality of electronic devices.

  In order to achieve such an object, the present invention provides a non-contact power transmission apparatus that supplies power from a power transmission coil to a power reception coil by electromagnetic induction, and includes a plurality of power transmission coils arranged substantially concentrically. Only the outermost power transmission coil and the inner power transmission coil are driven.

  According to the present invention, even when power is transmitted to a power receiving coil having a different outer shape with one power transmission device, generation of leakage magnetic flux can be suppressed.

Power transmission coil and first power receiving coil according to first embodiment of the present invention Power transmission coil and second power reception coil according to first embodiment of the present invention The circuit diagram of the power transmission apparatus and power receiving apparatus which concern on the 1st Embodiment of this invention Power transmission coil and first power receiving coil according to second embodiment of the present invention Modified example of the second power receiving coil of the present invention The circuit diagram of the power receiving apparatus provided with the 2nd power receiving coil of the modification of this invention Conventional power transmission coil and power reception coil

(First embodiment)
The power transmission coil according to the first embodiment of the present invention will be described. FIG. 1A is a cross-sectional view of the power transmission coil and the first power receiving coil, and FIG. 1B is a perspective view of the power transmission coil. The power transmission coils 11 and 12 are disposed substantially concentrically and on the same plane. The power transmission coil 12 located outside is formed in a ring shape. Magnetic sheets 13 and 23 are affixed to the surfaces opposite to the surfaces where the power transmission coils 11 and 12 and the first power receiving coil 21 face each other to suppress unnecessary radiation. The magnetic sheets 13 and 23 have the same size as or larger than that of the power transmission coil 12 and the first power receiving coil 21, respectively.

  The power transmission coil 11 located on the inner side and the power transmission coil 12 located on the outer side are individually controlled according to the outer shape of the first power receiving coil 21. First, as shown in FIG. 1, the case where the external shape of the 1st receiving coil 21 and the external shape of the power transmission coil 12 are substantially the same is demonstrated. The power transmission coils 11 and 12 and the first power reception coil 21 are arranged so that their central axes coincide. A first power receiving coil 21 is disposed on the winding surface of the power transmitting coil 11. On the other hand, the first power receiving coil 21 is not disposed on the winding surface of the power transmitting coil 12. When the power transmission coil 12 is driven in such a case, a leakage magnetic flux from the power transmission coil 12 is generated around the first power reception coil 21. Therefore, when power is transmitted to the first power receiving coil 21, only the power transmission coil 11 is driven and the power transmission coil 12 is not driven.

  Next, the case where the external shape of the 1st receiving coil 21 is enlarged is demonstrated. FIG. 2 shows a power transmission coil and a second power reception coil according to the first embodiment of the present invention. 2A is a cross-sectional view of the power transmission coil and the second power reception coil, and FIG. 2B is a perspective view of the power transmission coil. The power transmission coil shown in FIG. 2 is the same as the power transmission coil shown in FIG. The second power receiving coil 21 ′ has a larger outer shape than the first power receiving coil 21, and can receive larger power. The outer shape of the second power receiving coil 21 ′ is substantially the same as the outer shape of the power transmission coil 12. The power transmission coils 11 and 12 and the second power reception coil 21 ′ are arranged so that their central axes coincide. A second power receiving coil 21 ′ is disposed on the winding surface of each power transmitting coil 11, 12. When power is transmitted to the second power receiving coil 21 ′, larger power can be transmitted by driving both power transmission coils 11 and 12.

  Next, the control part of the power transmission coils 11 and 12 is demonstrated. FIG. 3 shows a circuit diagram of the power transmission device and the power reception device according to the first embodiment of the present invention.

  The power transmission device 10 includes power transmission coils 11 and 12, a drive circuit 15, a switching element 16, a Hall element 17, and resonant capacitors 18 and 19. A DC voltage is supplied to the drive circuit 15 from a DC power source Vin. The drive circuit 15 is an inverter having a full bridge configuration, and outputs AC power. A power transmission coil 11 and a resonance capacitor 18 are connected in series to the output portion of the drive circuit 15. In parallel therewith, a power transmission coil 12, a resonant capacitor 19, and a switching element 16 are connected in series. The hall element 17 is disposed in the vicinity of the power transmission coil 12. For example, the Hall element 17 is disposed around the outer periphery of the power transmission coil 12. As shown in FIG. 1, the power transmission coils 11 and 12 are arranged substantially concentrically, and a switching element 16 for switching is provided for the power transmission coil 12 located on the outside. As an example of the switching element 16, the loss can be reduced by configuring the two N-type MOSFETs to be connected in reverse series.

  The power receiving device 20 includes a second power receiving coil 21 ′, a rectifier circuit 25, a permanent magnet 27, and a resonant capacitor 28. The permanent magnet 27 is disposed in the vicinity of the second power receiving coil 21 '. For example, the permanent magnet 27 is disposed around the outer periphery of the power receiving coil 21 ′ so that the Hall element 17 can detect the magnetic flux generated from the permanent magnet 27 when the power receiving device 20 is placed on the power transmitting device 10. The resonant capacitor 28 is connected in parallel with the second power receiving coil 21 ′, and its output is supplied to a load such as a secondary battery via the rectifier circuit 25.

  Next, the operation of the switching element 16 will be described. When the second power receiving coil 21 ′ comes close to the power transmitting coil 12, the Hall element 17 detects the magnetic flux of the permanent magnet 27. Then, the switching element 16 is turned on by the detection signal Sg of the Hall element 17, and AC power is supplied from the drive circuit 15 to the power transmission coil 12. Then, as shown in FIG. 2, power is transmitted from both power transmission coils 11 and 12 to the second power reception coil 21 '.

  On the other hand, in the example shown in FIG. 1, since the outer shape of the first power receiving coil 21 is substantially the same as that of the inner power transmission coil 11, it is not necessary to drive the outer power transmission coil 12. When power is transmitted to the first power receiving coil 21, the permanent magnet 27 may not be provided in the power receiving device 20. Then, since the Hall element 17 cannot detect the magnetic flux of the permanent magnet 27, the switching element 16 remains off and only the power transmission coil 11 is driven. Thus, since the power transmission coil which drives according to the shape of a receiving coil can be determined, the leakage magnetic flux which generate | occur | produces from a power transmission coil can be suppressed.

  In the present embodiment, two power transmission coils are provided on the inner side and the outer side, but may be configured to be three or more. In that case, add the required number of power transmission coils, resonant capacitors, and switching elements to the output part of the drive circuit and connect them in series, and provide the same number of Hall elements to switch the switching elements in the vicinity of each power transmission coil. Good. Then, on the power receiving device side, a permanent magnet is provided at a position facing the corresponding hall element according to the power transmission coil to be driven. Thereby, it can respond to the receiving coil which has a more various external shape. Further, although a full bridge circuit is used as the drive circuit 15, a half bridge circuit may be used.

  Although the switching element 16 is switched from OFF to ON by the Hall element 17 detecting the magnetic flux of the permanent magnet 27, the generation of the switching signal of the switching element 16 is not limited to this method. For example, in the case of a power transmission / reception system with ID authentication, a dedicated ID signal is transmitted from the power reception device 20 to the power transmission device 10, and when the power transmission device 10 receives the signal, the switching element 16 is switched from off to on. You may do it. The method is not limited to these methods, and any method may be used as long as the power transmission coil to be driven can be appropriately selected according to each power reception coil having a different external shape.

(Second Embodiment)
A power transmission coil according to a second embodiment of the present invention will be described. FIG. 4 shows a power transmission coil and a first power reception coil according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the site | part which has the same function as 1st Embodiment, and description is abbreviate | omitted.

  As shown in FIG. 4, in this embodiment, a magnetic body 14 is additionally provided between the inner power transmission coil 11 and the outer power transmission coil 12 as compared with the power transmission coil of the first embodiment. The point is different. By adding this magnetic body 14, the coupling between the power transmission coils 11 and 12 is weakened. Thereby, when each power transmission coil 11 and 12 is driven simultaneously, it can suppress that a resonant frequency falls by the influence of the mutual inductance between the power transmission coils 11 and 12. FIG. Therefore, the power transmission coils 11 and 12 and the resonant capacitors 18 and 19 operate stably. By weakening the coupling between the power transmission coils 11 and 12, it is possible to prevent the drive current from decreasing and increase the transmission power. When the outer power transmission coil 12 is not driven, the magnetic body 14 suppresses the magnetic flux generated by the power transmission coil 11 from spreading in the side surface direction of the coil.

  The magnetic sheets 13 and 23 and the magnetic body 14 may be anything as long as they are magnetic materials. For example, a magnetic sheet, a ferrite core, an amorphous core, or the like may be used. Further, the magnetic sheet 13 and the magnetic body 14 may be integrally formed.

  Next, FIG. 5 shows a modification of the second power receiving coil. Similar to the power transmission coils 11 and 12, a plurality of power reception coils are provided concentrically. The power transmission coils 11 and 12 and the power reception coils 21 and 22 are arranged so that their central axes coincide. The inner power receiving coil 21 has substantially the same outer shape as the inner power transmitting coil 11, and the outer power receiving coil 22 has substantially the same outer shape as the outer power transmitting coil 12. Therefore, the inner power receiving coil 21 is disposed on the winding surface of the power transmission coil 11, and the outer power receiving coil 22 is not disposed on the winding surface of the power transmission coil 12. Similar to the example shown in FIG. 2, it is possible to transmit larger power by driving both power transmission coils 11 and 12.

  FIG. 6 is a circuit diagram of a power receiving device including the second power receiving coil of the modification shown in FIG. The power receiving coils 21 and 22 are connected in parallel via the rectifier circuits 25. With this configuration, the current flowing through each rectifier circuit 25 is halved as compared with the case where one power receiving coil is used when the same output current is obtained. Therefore, it is possible to operate in a state where the forward voltage drop of the diode in each rectifier circuit 25 is low. Thus, loss in the diode can be reduced and efficiency can be improved.

  In the first and second embodiments, the case where the outer shape of the power receiving coil is substantially the same as the outer shape of the inner or outer power transmitting coil is described, but the outer shape of the power receiving coil is different from any of the plurality of power transmitting coils. There is also. In such a case, you may determine the power transmission coil to drive according to the diameter and area of a receiving coil. When the diameter of the power receiving coil is smaller than the diameter of the inner power transmission coil, only the inner power transmission coil is driven. When the diameter of the power receiving coil is larger than the diameter of the outer power transmitting coil, the inner and outer power transmitting coils are driven. When the diameter of the power receiving coil is larger than the diameter of the inner power transmitting coil and smaller than the diameter of the outer power transmitting coil, for example, a power transmitting coil that is driven depending on whether the diameter of the power receiving coil is closer to the diameter of the inner power transmitting coil or the outer power transmitting coil. decide. When the diameter of the power receiving coil is close to the diameter of the inner power transmitting coil, only the inner power transmitting coil is driven. When the diameter of the power receiving coil is close to the diameter of the outer power transmitting coil, the inner and outer power transmitting coils are driven.

  When three or more power transmission coils are used, only the power transmission coil having the outer shape closest to the outer shape of the power receiving coil and the power transmission coil inside the power transmission coil may be driven. For example, a method of driving only a power transmission coil having a diameter closest to the diameter of the power reception coil and a power transmission coil inside the power transmission coil can be considered. As described above, a power transmission coil to be driven may be selected according to the area of the power reception coil. In any condition, when the power transmission coil having the outer shape closest to the outer shape of the power receiving coil is the innermost power transmission coil, only the power transmission coil is driven.

  In the present invention, a plurality of power transmission coils are arranged substantially concentrically and on the same plane, and a power transmission coil to be driven is appropriately selected and controlled for power reception coils having different external shapes. Specifically, only the power transmission coil having the outer shape closest to the outer shape of the power receiving coil and the power transmission coil inside the power transmission coil are driven. In other words, by switching the switching element connected to the power transmission coil, control is performed so that the shape of the winding surface of the power transmission coil to be driven matches the shape of the winding surface of the power reception coil as much as possible. Thereby, in one power transmission coil, electric power transmission can be performed with respect to various power receiving coils having different power requirements without changing the drive frequency. At that time, leakage magnetic flux generated from the power transmission coil can be suppressed. In particular, by making the outer shape of the power receiving coil substantially the same as the outer shape of any one of the power transmission coils, it is possible to further suppress the generation of leakage magnetic flux.

  In addition, although the shape of the winding surface of the power transmission coil was circular, it may be changed to another shape. For example, an arbitrary shape such as a polygonal shape such as a quadrangle or a triangle can be used. Moreover, as an example, you may arrange | position combining the power transmission coil of a different shape, such as arrange | positioning a circular power transmission coil inside, and arrange | positioning a square power transmission coil outside.

DESCRIPTION OF SYMBOLS 10 Power transmission apparatus 11, 12 Power transmission coil 13 Magnetic sheet 14 Magnetic body 15 Drive circuit 16 Switching element 17 Hall element 18, 19 Resonance capacitor 20 Power receiving apparatus 21, 21 ', 22 Power receiving coil 23 Magnetic sheet 25 Rectifier circuit 27 Permanent magnet 28 Resonance Capacitor

Claims (7)

In a non-contact power transmission apparatus that supplies power by electromagnetic induction from a power transmission coil to a power reception coil
It has a plurality of power transmission coils arranged in a substantially concentric circle shape,
The plurality of power transmission coils are connected in parallel,
A non-contact power transmission device that drives only a power transmission coil having an outer shape closest to the outer shape of the power receiving coil and a power transmission coil inside the power transmission coil. In a non-contact power transmission apparatus that supplies power by electromagnetic induction from a power transmission coil to a power reception coil
It has a plurality of power transmission coils arranged in a substantially concentric circle shape,
A magnetic body is provided between the plurality of power transmission coils,
A non-contact power transmission device that drives only a power transmission coil having an outer shape closest to the outer shape of the power receiving coil and a power transmission coil inside the power transmission coil. In a non-contact power transmission apparatus that supplies power by electromagnetic induction from a power transmission coil to a power reception coil
It has a plurality of power transmission coils arranged in a substantially concentric circle shape,
The plurality of power transmission coils are connected in parallel,
A magnetic body is provided between the plurality of power transmission coils,
A non-contact power transmission device that drives only a power transmission coil having an outer shape closest to the outer shape of the power receiving coil and a power transmission coil inside the power transmission coil. The power receiving coil, a non-contact power transmission device according to any one of claims 1 to 3 or the outer shape of the plurality of power transmission coils, characterized in that it is substantially the same. The contactless power transmission device according to any one of claims 1 to 3, wherein the power receiving coil includes a plurality of power receiving coils that are arranged substantially concentrically and connected in parallel. The plurality of power transmission coils are composed of a first power transmission coil and a second power transmission coil disposed outside the first power transmission coil,
When the outer shape of the power receiving coil is closer to the outer shape of the first power transmission coil than the outer shape of the second power transmission coil, only the first power transmission coil is driven,
When the outer shape of the power receiving coil is closer to the outer shape of the second power transmission coil than the outer shape of the first power transmission coil, the first power transmission coil and the second power transmission coil are driven. The non-contact power transmission apparatus according to claim 1 . The outer shape of the power receiving coil is substantially the same as the outer shape of the first power transmission coil or the second power transmission coil,
When the outer shape of the power receiving coil is substantially the same as the first power transmission coil, only the first power transmission coil is driven. When the outer shape of the power receiving coil is substantially the same as the second power transmission coil, the first power transmission coil is driven. The contactless power transmission device according to claim 6 , wherein the coil and the second power transmission coil are driven.

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