JP2018143058A - Transmission apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission apparatus with high charging efficiency by suppressing an adverse effect of mutual inductance between two transmission coils conforming to different standards.SOLUTION: A transmission apparatus 100 includes a transmission circuit 41 for generating an electric signal; a first transmission coil 10 for transmitting electric power by means of a first transmission system with an electric signal generated by the transmission circuit; and a second transmission coil 20 for transmitting electric power by means of a second transmission system with an electric signal generated by the transmission circuit. The transmission circuit, when generating an electric signal to transmit electric power from the second transmission coil, generates the electric signal to the fist transmission coil so that an electric current flows in an opposite direction to a flowing direction of an electric current generated by interlinking a magnetic flux generated from the second transmission coil to the first transmission coil.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power transmission device that wirelessly transmits power to a power receiving device, and more particularly to a power transmission device that transmits power in a contactless manner by coexisting two different types of coils.

  Conventionally, a power transmission device that wirelessly transmits power to a power receiving device has been proposed. For example, Patent Literature 1 discloses a wireless power transmission system that can support two transmission methods and can suppress a decrease in transmission efficiency from a power transmission device to a power reception device. This wireless power transmission system wirelessly transmits power from a power transmission device to a power reception device by using magnetic field coupling between the power transmission coil and the power reception coil. The power transmission device includes a power transmission circuit that generates an electrical signal for power transmission, a first power transmission coil corresponding to the first transmission method, a second power transmission coil corresponding to the second transmission method, and a first power transmission coil. It has the 1st magnetic body mounted on it, the 2nd magnetic body on which the 2nd power transmission coil is mounted on it, and the electric power feeding surface where the power receiving apparatus is mounted on it. The first mounting surface of the first magnetic body and the second mounting surface of the second magnetic body are located below the power feeding surface and are disposed on the same plane parallel to the power feeding surface. In this power transmission device, the magnetic flux generated by the first power transmission coil can be concentrated inside the first magnetic body, and magnetic field coupling between the first power transmission coil and the second power transmission coil can be suppressed. Further, the magnetic flux generated by the second power transmission coil can be concentrated inside the second magnetic body, and magnetic field coupling between the first power transmission coil and the second power transmission coil can be suppressed.

  Patent Document 2 discloses a magnetic coupling device capable of reducing energy loss when performing an operation using magnetic coupling between magnetic elements. This magnetic coupling device includes one or a plurality of magnetic elements capable of mutual magnetic coupling with another magnetic element in another device, and one or a plurality of coupling reinforcing portions for reinforcing the magnetic coupling. . The coupling reinforcing portion includes first and second current generation portions that are electrically connected to each other, and the direction in which the first current generated in the first current generation portion flows and the second current generation portion The directions in which the generated second current flows are opposite to each other.

  Patent Document 3 discloses a non-contact type power transmission device that suppresses the variation of the coupling coefficient even when the position of the power receiving coil varies with respect to the power transmitting coil. This power transmission device includes a power transmission coil, a power transmission device including an AC power source that supplies AC power to a resonance element including the power transmission coil, a power reception coil that receives power in a contactless manner by magnetic coupling, and a resonance element including the power reception coil A power transmission device including a rectifier circuit that rectifies AC power induced in the power. The power transmission coil surrounds the first region in which the forward transmission line and the reverse transmission line are alternately arranged in the center, and the first region is electrically connected to the forward line in the first region. A first planar coil pattern having a second region provided with a directional line, and the power receiving coil includes a planar second coil pattern arranged to face the first region. .

Japanese Patent Laying-Open No. 2015-144508 JP 2013-102593 A Japanese Patent Laid-Open No. 2006-051793

  In recent years, with the spread of mobile terminals such as smartphones, a plurality of standards for performing contactless charging have appeared. For example, there are Qi standards, PMA standards, A4WP standards, and the like, which are mutually compatible in both hardware and software. The Qi standard and the PMA standard employ an electromagnetic induction method and can share hardware (power transmission coil). On the other hand, the A4WP standard employs a magnetic field resonance method, and the power transmission coil is not compatible with the Qi standard or the like, and a dedicated power transmission coil is required. In consideration of the user's ease of use, it is preferable that one non-contact charger can support a plurality of standards.

  However, when both the power transmission coil compliant with the Qi standard / PMA standard and the power transmission coil compliant with the A4WP standard are arranged in a miniaturized device, the coils interfere with each other due to the mutual inductance, so that the inductance value Fluctuates and causes a decrease in charging performance. It has been found that this performance degradation is noticeable in the case of the magnetic field resonance method such as the A4WP standard.

  The present invention has been devised in view of such circumstances, and provides a power transmission device with good charging efficiency by reducing the influence of mutual inductance in two power transmission coils conforming to different standards.

In order to solve the above-described problem, a power transmission device that wirelessly transmits power to a power receiving device, the power transmission circuit generating an electrical signal, and the power transmitted by the first transmission method using the electrical signal generated by the power transmission circuit A first power transmission coil, and a second power transmission coil configured to transmit power by the second transmission method using an electrical signal generated by the power transmission circuit, wherein the power transmission circuit transmits the power from the second power transmission coil. Is generated, the magnetic flux generated from the second power transmission coil is interlinked with the first power transmission coil so that the current flows in a direction opposite to the direction in which the current flows. A power transmission device for generating a signal is provided.
According to this, when transmitting power from one power transmission coil, by controlling the current to flow in the direction opposite to the direction of the current flowing in the other power transmission coil by the magnetic flux generated from the power transmission coil, It is possible to provide a power transmission device with good charging efficiency by making it difficult for current to flow through the other power transmission coil and reducing the influence of mutual inductance.

Furthermore, the power transmission circuit may optimize the value of the current flowing through the first power transmission coil by generating an electrical signal so as to change the current flowing in the opposite direction.
According to this, by continuously changing the value of the current in the reverse direction with respect to the other power transmission coil, it is possible to search for the current value and obtain the optimum value of the current value flowing through the other power transmission coil.

Further, the optimization may be performed such that the power transmitted by the second power transmission coil is maximized.
According to this, the efficiency of charging by one coil is improved by optimizing so that the power transmitted by one coil is maximized.

Furthermore, a current value measuring unit that measures a current value flowing through the second power transmission coil is further provided, and the optimization is performed by adjusting the current value measured by the current value measuring unit within a range in which the current flowing in the opposite direction is changed. It may be performed by selecting a value of a current that flows in a reverse direction when a high current value is shown.
According to this, the efficiency of charging by one coil is improved by selecting the current value in the reverse direction in the other coil when the highest current value is shown in one coil.

Further, the optimization may be repeated by repeatedly changing the current flowing in the opposite direction.
According to this, efficient charging by one coil can be continued by repeatedly changing the value of the current in the reverse direction with respect to the other power transmission coil.

Furthermore, the first power transmission coil may be a coil corresponding to an electromagnetic induction method, and the second power transmission coil may be a coil compatible with a magnetic field resonance method.
According to this, in the charging device compliant with both the magnetic resonance method and the electromagnetic induction method, when electric power is transmitted from the magnetic resonance type power transmission coil, the electromagnetic induction type power transmission is performed by the magnetic flux generated from the power transmission coil. By controlling the current to flow in the direction opposite to the direction of the current flowing in the coil, it is difficult for the current to flow in the electromagnetic induction type power transmission coil, reducing the influence of mutual inductance, and magnetic field resonance type power transmission. It is possible to provide a power transmission device with good charging efficiency in charging by a coil.

  As described above, according to the present invention, it is possible to provide a power transmission device with good charging efficiency by reducing the influence of mutual inductance in two charging coils conforming to different standards.

BRIEF DESCRIPTION OF THE DRAWINGS (A) Top view (except the case containing a feeding surface), (B) Side view (Case shows only a feeding surface) of the power transmission apparatus of the first embodiment according to the present invention. The flowchart which shows the control method in the power transmission apparatus of 1st Example which concerns on this invention. In the power transmission device of the prior art, (A) a schematic diagram showing that a current flows through the electromagnetic induction coil by the magnetic flux generated by the magnetic field resonance coil, and (B) a current between the power receiving device due to the current flowing through the electromagnetic induction coil. The schematic diagram which shows that coupling | bonding generate | occur | produces.

  Embodiments according to the present invention will be described below with reference to the drawings. First, a conventional power transmission device 100Z will be described with reference to FIG. In this figure, the casing of the power transmission device 100Z is not shown, and the coil and the like housed in the casing are shown in the center. The power transmission device 100Z is a power transmission device that wirelessly transmits power to a power receiving device RD such as a smartphone. The power receiving device RD has a power receiving function that can be applied to the transmission method of the power transmitting device 100Z inside, and receives power from the power transmitting device 100Z by being placed on the power feeding surface 60 of the casing of the power transmitting device 100Z. Is charged.

  The power transmission device 100Z includes a first power transmission coil 10 that transmits power by an electromagnetic induction method and a second power transmission coil 20 that transmits power by a magnetic field resonance method. The electromagnetic induction method is a method for transmitting electric power by generating an electromotive force in the coil on the power receiving side by electromagnetic induction generated in accordance with a change in the magnetic field generated by the coil on the power transmission side. The magnetic field resonance system is a power-reception-side resonance circuit in which the frequency of the magnetic field generated by the current flowing through the coil on the power transmission side is resonated at the same frequency by combining the frequency of the coil on the power transmission side and the frequency of the coil on the power reception side. This is a method of transmitting power by being transmitted.

  In the electromagnetic induction system, the magnitude of the magnetic flux greatly affects the power transmission efficiency, and the magnitude of the coupling coefficient between the coils on the power transmission side and the power reception side determines the magnitude of the transmission power. The magnitude of the coupling coefficient is affected by the distance between the coils and the degree of coincidence of the coil center positions. In the magnetic field resonance method, the magnetic flux may be small. Instead, the high peaky performance (property that reacts sensitively to a predetermined frequency) in the coil (antenna) on the power transmission side and the power reception side greatly affects the transmission efficiency. . In the magnetic field resonance method, the magnitude of the magnetic flux has little relation to the transmission efficiency, so that there is a feature that power transmission is possible even if the power transmission side coil and the power reception side coil are separated from each other. Easy to be affected by magnetic flux. That is, in the transmission efficiency of the magnetic field resonance method, it is important how much the resonance frequency of the coil on the power transmission side and the resonance frequency of the coil on the power reception side can be matched.

  In particular, in a power transmission device including the first power transmission coil 10 of the electromagnetic induction method and the second power transmission coil 20 of the magnetic field resonance method, such as the power transmission device 100Z, the influence of the mutual inductance of the power transmission side coil and the power reception side coil is affected. Will receive. That is, in the vicinity of the magnetic field resonance type second power transmission coil 20, the power reception coil of the power reception device RD that is close to the vicinity in order to increase the transmission efficiency in the electromagnetic induction system, together with its own electromagnetic induction type first power transmission coil 10. Because it exists.

  As shown in this figure, in the power transmission device 100Z, the electromagnetic induction type first power transmission coil 10 and the magnetic field resonance type second power transmission coil 20 are located in the vicinity of the power supply surface 60, that is, in the vicinity of the power reception device RD. The distance from the coil on the power receiving side of the RD is substantially the same for both. This figure (A) shows that the upward magnetic flux ML was generated by passing a current through the magnetic field resonance type second power transmission coil 20. Then, the magnetic flux ML is linked to the electromagnetic induction type first power transmission coil 10, and the current CR flows to the electromagnetic induction type first power transmission coil 10 by the amount of this linkage.

  Then, as shown in this figure (B), coupling | bonding generate | occur | produces between the 1st power transmission coil 10 of an electromagnetic induction system, and the coil of the power receiving side of power receiving apparatus RD. When such coupling occurs, the mutual inductance changes and the resonance frequency of the coil on the power receiving side fluctuates. Therefore, the peaky performance is high, so that the transmission efficiency in the second power transmission coil 20 of the magnetic field resonance method is reduced. Become. In addition, the mutual inductance may vary even when the smartphone of the power receiving device RD moves on the power feeding surface 60 and the distance between the first power transmission coil 10 / second power transmission coil 20 and the power receiving coil varies. . When the fluctuation of the mutual inductance as described above occurs, the charging performance of the power transmitting device 100Z with respect to the power receiving device RD is reduced.

<First Example>
With reference to FIG. 1, the power transmission apparatus 100 in a present Example is demonstrated. Note that FIG. 1A does not show the case of the power transmission device 100, and shows only the internal coil and the like. FIG. 1B shows only the power feeding surface 60 in this case. The power transmission device 100 is a device that wirelessly transmits power to a power receiving device RD such as a portable terminal, and includes a power feeding surface 60 on which the power receiving device RD is placed. The power transmission device 100 is a so-called wireless charging method for supplying power wirelessly to a power receiving device RD such as a portable terminal. Includes both magnetic resonance methods using electromagnetic waves with frequencies near MHz.

  In order to correspond to the two types of wireless charging methods, the power transmission device 100 uses a first power transmission coil 10 that transmits power by an electromagnetic induction method (first transmission method) and a magnetic field resonance method (second transmission method). And a second power transmission coil 20 that transmits electric power. More specifically, the power transmission device 100 is laminated on the control board 40 having a rectangular shape in plan view, the magnetic body 30 for enhancing the magnetic field in a rectangular plate shape on the control board 40, and the power supply surface 60 side of the magnetic body 30. The first power transmission coil 10 provided in this manner, the second power transmission coil substrate 21 provided in parallel with the control board 40 and electrically connected to the control board 40, and the second power transmission coil board 21 The 2nd power transmission coil 20 provided in is provided.

  The 1st power transmission coil 10 is arrange | positioned so that it may fit in the opening part 22 of the 2nd power transmission coil board | substrate 21. FIG. Therefore, the distance from the power feeding surface 60 of the first power transmission coil 10 is arranged at a position substantially the same as the distance from the power feeding surface 60 of the second power transmission coil 20, and the first power transmission coil 10 is connected to the second power transmission coil 10. Located on the coil center side of the coil 20. The magnetic body 30 is made of a material having a magnetic permeability of 1 or more, such as ferrite, and has a rectangular plate shape. The shape in plan view is substantially the same as the rectangular shape of the opening 22 of the second power transmission coil substrate 21. And is arranged so as to coincide with the opening 22. The first power transmission coil 10 is a spiral coil wound in a square ring shape with a conductor wiring pattern formed on the control board 40.

  The 2nd power transmission coil 20 is provided in the frame part pinched | interposed into the opening part 22 of the 2nd power transmission coil board | substrate 21, and an outer peripheral part. The second power transmission coil 20 is an antenna formed in a rectangular shape by a conductor wiring pattern formed on the second power transmission coil substrate 21, and unlike the first power transmission coil 10 coupled by the strength of magnetic flux, the magnetic field resonance. Therefore, it is not always necessary to wind it many times. The second power transmission coil 20 resonates at a predetermined frequency due to its own inductance and stray capacitance.

  The power transmission device 100 further includes a power transmission circuit 41 that generates electrical signals for the first power transmission coil 10 and the second power transmission coil 20 on the control board 40. The power transmission circuit 41 includes a first power transmission circuit corresponding to the first power transmission coil 10 and a second power transmission circuit corresponding to the second power transmission coil 20, which are configured by a circuit such as an inverter circuit. The first power transmission circuit generates an electric signal for power transmission corresponding to the electromagnetic induction method. As an electrical signal corresponding to the electromagnetic induction method, an alternating electrical signal having a frequency in the vicinity of several tens of kHz to several hundreds of kHz is usually used. The second power transmission circuit generates an electric signal for power transmission corresponding to the magnetic resonance method. As an electrical signal corresponding to the magnetic resonance system, an alternating electrical signal having a frequency in the vicinity of several MHz to several tens of MHz is usually used.

  In addition to the power transmission circuit 41, the control board 40 includes a detection circuit, a control circuit, a switch, and the like (not shown). Based on a predetermined control signal and operation, an electromagnetic induction method and a magnetic resonance method are used. Either transmission method can be selected. The power transmission circuit 41 applies the generated electrical signal to the first power transmission coil 10 or the second power transmission coil 20 of the selected method. The detection circuit is installed in the vicinity of the power supply surface 60 and detects whether the power receiving device RD is an electromagnetic induction type power receiving device or a magnetic field resonance type power receiving device by detecting the signal of the power receiving device RD, for example. It is determined by the frequency of the signal. Moreover, the power transmission circuit 41 can be simultaneously applied to the first power transmission coil 10 and the second power transmission coil 20 as necessary.

  With reference to FIG. 2, the control method at the time of the power transmission circuit 41 producing | generating an electric signal with respect to the 1st power transmission coil 10 and the 2nd power transmission coil 20 is demonstrated. In addition, S in the flowchart means a step. This figure demonstrates the case where it charges with respect to the receiving device RD of a magnetic field resonance system. In S100, the power transmission device 100 detects which type of power reception device RD has approached the power supply surface 60 using the detection circuit, and detects that the magnetic field resonance type power reception device RD has approached from the frequency or the like. In S102, the power transmission circuit 41 of the power transmission device 100 generates and applies an electric signal having a frequency corresponding to the magnetic field resonance method to the second power transmission coil 20 in order to transmit power to the magnetic resonance type power receiving device RD. . Thereby, the power transmission apparatus 100 starts power transmission by the magnetic field resonance type second power transmission coil 20.

  The power transmission circuit 41 generates and applies an electric signal so as to transmit electric power to the magnetic field resonance type second power transmission coil 20, and in S104, the reverse direction is applied to the electromagnetic induction type first power transmission coil 10. An electric signal is generated and applied so that the current flows. Here, the reverse current will be described. When an electric signal is generated so that electric power is transmitted from the magnetic field resonance type second power transmission coil 20, magnetic flux is generated from the second power transmission coil 20. The magnetic flux generated by the second power transmission coil 20 is linked to the first power transmission coil 10 located on the coil center side of the second power transmission coil 20, so that a current flows through the first power transmission coil 10. .

  The reverse current refers to a current in the reverse direction with respect to the current flow that is about to flow through the first power transmission coil 10. That is, a current in a direction opposite to the current that is about to flow to the first power transmission coil 10 by flowing the magnetic flux generated by the second power transmission coil 20 is interlinked, so that a current substantially flows through the first power transmission coil 10. Is to prevent the flow. For example, when an AC electrical signal having a frequency of 6.78 MHz is input to the second power transmission coil 20 in order to transmit power from the second power transmission coil 20 of the magnetic field resonance method, an AC electrical signal having the same frequency of 6.78 MHz is input. Then, an electrical signal that causes a current in a direction opposite to the current to flow through the first power transmission coil 10 is input to the first power transmission coil 10. By controlling in this way, the coupling | bonding which generate | occur | produces between the 1st power transmission coil 10 and the coil of the power receiving side of the power receiving apparatus RD can be suppressed.

  That is, when the power transmission circuit 41 generates an electric signal so as to transmit power from the magnetic field resonance type second power transmission coil 20, the magnetic flux generated from the second power transmission coil 20 is linked to the first power transmission coil 10. An electric signal is generated with respect to the first power transmission coil 10 so that the current flows in a direction opposite to the direction in which the generated current flows. Thus, in a charging device compliant with both magnetic resonance and electromagnetic induction standards, when transmitting power from a magnetic resonance transmission coil, the electromagnetic induction transmission coil is caused by the magnetic flux generated from the transmission coil. By controlling the current to flow in the direction opposite to the direction of the current flowing in the electromagnetic induction type, it is difficult for the current to flow in the electromagnetic induction type power transmission coil, reducing the influence of mutual inductance, and the magnetic field resonance type power transmission coil. Thus, it is possible to provide the power transmission device 100 with good charging efficiency in charging by the above.

  In S106, the power transmission circuit 41 continuously changes the current value of the reverse current flowing through the first power transmission coil 10 to optimize the current value. The amount of current flowing in the reverse direction varies depending on the position and performance of the power receiving device RD, so that the coupling between the power receiving device RD and the coil on the power receiving side does not occur. The magnitude of the current value cannot be determined as one. Therefore, the amount of electric power transmitted from the second magnetic field resonance type second power transmission coil 20 is detected while increasing the current value of the reverse current, for example, every 1 mA from 1 mA to 100 mA, and the detected value is the largest. The reverse current value is selected as the optimum current value.

  That is, the power transmission circuit 41 optimizes the value of the current flowing through the first power transmission coil 10 by generating an electrical signal so as to change the current flowing in the opposite direction. According to this, the optimum value of the current value flowing through the first power transmission coil 10 can be obtained by searching for the current value flowing through the first power transmission coil 10. This optimization is performed so that the power transmitted by the second power transmission coil 20 is maximized, and as a result, the efficiency of charging by the magnetic field resonance type second power transmission coil 20 is improved.

  Note that the amount of power transmitted from the second power transmission coil 20 may be detected by the current value of the second power transmission coil 20. That is, the power transmission device 100 further includes a current value measurement unit 42 that measures a current value flowing through the second power transmission coil 20, and the optimization of the current value flowing through the first power transmission coil 10 is performed in a range in which the reverse current is changed. This may be performed by selecting the current value of the reverse current when the current value measured by the current value measuring unit 42 indicates the highest current value. Thereby, as a result, the efficiency of charging by the second power transmission coil 20 is improved.

  In S108, the power transmission circuit 41 waits for a predetermined time after the optimization of the current value of the reverse current in S106. In S110, the power transmission circuit 41 again detects the amount of power transmitted from the second power transmission coil 20 (or the current value flowing through the second power transmission coil 20), and checks whether there is a change. While there is no fluctuation, it is assumed that the current optimized current value is valid, and the current value continues to flow through the first power transmission coil 10. On the other hand, if there is a change, in S106 again, the current value of the reverse current flowing through the first power transmission coil 10 is continuously changed to optimize the current value. As described above, the optimization may be repeated by repeatedly changing the current flowing in the opposite direction. In this way, by repeatedly changing the value of the current in the reverse direction with respect to the first power transmission coil 10, efficient charging by the magnetic field resonance type second power transmission coil 20 can be continued.

  In addition, this invention is not limited to the illustrated Example, The implementation by the structure of the range which does not deviate from the content described in each item of a claim is possible. That is, although the present invention has been particularly illustrated and described with respect to particular embodiments, it should be understood that the present invention has been described in terms of quantity, quantity, and amount without departing from the scope and spirit of the present invention. In other detailed configurations, various modifications can be made by those skilled in the art.

RD Power receiving device (mobile terminal)
100 power transmission device 10 first power transmission coil (electromagnetic induction coil)
20 Second power transmission coil (magnetic resonance coil)
DESCRIPTION OF SYMBOLS 21 2nd power transmission coil board | substrate 22 Opening part 30 Magnetic body 40 Control board 41 Power transmission circuit 42 Current value measurement part 60 Power feeding surface ML Magnetic field line

Claims (6)

A power transmission device that wirelessly transmits power to a power receiving device,
A power transmission circuit for generating an electrical signal;
A first power transmission coil that transmits power by a first transmission method using an electrical signal generated by the power transmission circuit;
A second power transmission coil that transmits electric power by a second transmission method using an electrical signal generated by the power transmission circuit;
With
When the power transmission circuit generates an electric signal so as to transmit electric power from the second power transmission coil, a magnetic flux generated from the second power transmission coil interlinks with the first power transmission coil. Generating an electrical signal for the first power transmission coil so that a current flows in a direction opposite to the flowing direction;
Power transmission device.   The said power transmission circuit optimizes the electric current value which flows into a said 1st power transmission coil by producing | generating an electrical signal so that the electric current sent in the said reverse direction may be changed. Power transmission device.   The power transmission apparatus according to claim 2, wherein the optimization is performed such that the power transmitted by the second power transmission coil is maximized. A current value measuring unit for measuring a current value flowing through the second power transmission coil;
In the optimization, the value of the current flowing in the reverse direction when the highest current value among the current values measured by the current value measurement unit is shown in the range in which the current flowing in the reverse direction is changed. The power transmission device according to claim 3, wherein the power transmission device is selected.   The power transmission device according to claim 4, wherein the optimization is repeated by repeatedly changing a current flowing in the reverse direction. The first power transmission coil is a coil corresponding to an electromagnetic induction method,
The power transmission device according to claim 1, wherein the second power transmission coil is a coil corresponding to a magnetic field resonance method.