JP2013225961A - Power receiving device, power transmitting device and power transmitting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve certainty of power transmission to an electronic apparatus while suppressing reduction in efficiency of power transmission.SOLUTION: A power receiving device is configured to receive power, through electromagnetic induction, from a power transmitting device 1 comprising a power transmitting coil 5 which is formed by spirally winding a conductor. The power receiving device comprises a power receiving coil 6 which is formed by spirally winding a conductor, and a load circuit section 202 to which power is supplied via the power receiving coil 6. An inductance value of the power receiving coil 6 is a value on the basis of a coupling coefficient in the case where at least a part of the power receiving coil 6 is positioned between an inner ring and an outer ring of the power transmitting coil 5.

Description

  The present invention relates to a wireless power transmission system that wirelessly transmits power from a power transmission device to a power reception device, and more particularly to a wireless power transmission system that can receive power in a wide range.

  In recent years, contactless charging (wireless power transmission) has been attracting attention, in which power is transmitted directly to an electronic device equipped with a two-hour battery without using a power feeding cable. The electronic device and the power transmission device of the electronic device each have a coil, and electric power is transmitted to the electronic device by generating electromagnetic induction between the two coils. Various techniques have been proposed to increase the efficiency of this non-contact power transmission.

  For example, a resonance circuit having a capacitor is provided in the coils for power transmission and power reception, and the values of the capacitance of the capacitor and the inductance of the coil are adjusted in order to increase the efficiency of power transmission. In order to adjust these values without trial and error, power is transmitted by reducing the impedance of the power supply circuit of the power transmission device and the load circuit of the electronic device to a specific resistance value (inductive resistance) that matches the coil. (See Patent Document 1).

WO2009 / 037821

  In the above (Patent Document 1), the coupling coefficient between the power transmission coil and the power reception coil is also used to adjust the capacitance value and the inductance value, but the coupling coefficient changes depending on the positional relationship between the power transmission coil and the power reception coil. The calculated capacitance value and inductance value vary depending on the positional relationship in which the coupling coefficient is used.

  Generally, the coupling coefficient increases when the centers of the power transmission coil and the power reception coil coincide. Therefore, in order to maximize the transmission efficiency, the capacitance value and the inductance value are adjusted so that the transmission efficiency is maximized when the centers of the power transmission coil and the power reception coil coincide.

  However, when the power receiving coil is located at the end of the power transmitting coil, the magnetic coupling between the power transmitting and receiving coils is reduced, and thus it is difficult for the power receiving device having the power receiving coil to receive power. That is, since the power receiving device can receive power only when the power receiving coil is located near the center of the power transmitting coil, the range in which the power receiving coil can receive power is limited.

  In view of the above problems, an object of the present invention is to widen the power receiving range of the power receiving coil.

  In order to solve the above problems, a power receiving device according to the present invention is a receiving device that receives power by electromagnetic induction from a power transmitting device having a power transmitting coil formed by winding a conductor in a spiral shape, and the conductor is spirally shaped. And a load circuit unit to which electric power is supplied via the power receiving coil, and an inductance value of the power receiving coil is such that at least a part of an inner ring of the power receiving coil is the power transmitting This value is based on the coupling coefficient when the coil is located between the inner ring and the outer ring.

  The power transmission device of the present invention is a power transmission device that transmits power by electromagnetic induction to a power receiving device having a power receiving coil formed by winding a conductor in a spiral shape, and is formed by winding a conductor in a spiral shape. A power transmission circuit that supplies power to the power transmission coil, and the inductance value of the power transmission coil is such that at least a part of the inner ring of the power reception coil is between the inner ring and the outer ring of the power transmission coil. It is a value based on the coupling coefficient when positioned.

  The power transmission system of the present invention is a power transmission system that performs power transmission by electromagnetic induction, and includes a transmission circuit unit having a power transmission coil and a power reception coil formed by winding a conductor in a spiral shape, and the power transmission coil A power circuit section for supplying power to the power supply circuit, and a load circuit section for supplying power via the power receiving coil, wherein the power transmission coil and the power receiving coil have inductance values at least part of the inner ring of the power receiving coil. Is a value based on the coupling coefficient when the power transmission coil is located between the outer ring and the inner ring.

  Since the power receiving device, the power transmitting device, and the power transmission system of the present invention are configured as described above, the range in which the power receiving device can receive power can be expanded.

1 is a circuit configuration diagram of a wireless power transmission system according to an embodiment of the present invention. 1 is a conceptual diagram of a circuit configuration of a wireless power transmission system according to an embodiment of the present invention. The perspective view of the 1st example of the wireless power transmission system which concerns on embodiment of this invention The top view of the 1st example of the wireless power transmission system concerning an embodiment of the invention Sectional drawing of the 1st example of the wireless power transmission system which concerns on embodiment of this invention The figure for demonstrating the positional relationship of the power transmission apparatus and electronic device which concern on embodiment of this invention The figure which shows the relationship between the coupling coefficient which concerns on embodiment of this invention, and the position of a receiving coil The figure which shows the relationship between the output voltage which concerns on embodiment of this invention, and the position of a receiving coil The figure which shows the relationship between the output voltage which concerns on a comparative example, and the position of a receiving coil The perspective view of the 2nd example of the wireless power transmission system which concerns on embodiment of this invention

  The power receiving device of the present invention is a receiving device that receives power by electromagnetic induction from a power transmitting device having a power transmitting coil formed by winding a conductor in a spiral shape, and is a power receiving device formed by winding a conductor in a spiral shape A coil and a load circuit unit to which electric power is supplied via the power receiving coil, and the inductance value of the power receiving coil is such that at least a part of the inner ring of the power receiving coil is between the inner ring and the outer ring of the power transmitting coil. It is a value based on the coupling coefficient in the case of being located.

  In the power receiving device of the present invention, the inductance value of the power receiving coil is a value based on the impedance value of the load circuit unit.

  The power receiving device of the present invention further includes a capacitor connected in series to the power receiving coil and resonating with the power receiving coil.

  In the power receiving device of the present invention, the inductance value of the power receiving coil is a value based on a coupling coefficient when the power receiving coil is positioned closer to the outer ring of the power transmitting coil than the inner ring of the power transmitting coil.

  As described above, since the inductance value of the power receiving coil is a value based on the coupling coefficient when the power receiving coil is located at the end of the power transmitting coil, the power receiving device can receive power in a wide range.

  The power transmission device of the present invention is a power transmission device that transmits power by electromagnetic induction to a power receiving device having a power receiving coil formed by winding a conductor in a spiral shape, and is formed by winding a conductor in a spiral shape. A power transmission circuit that supplies power to the power transmission coil, and the inductance value of the power transmission coil is such that at least a part of the inner ring of the power reception coil is between the inner ring and the outer ring of the power transmission coil. It is a value based on the coupling coefficient when positioned.

  The power transmission device of the present invention further includes a capacitor connected in series to the power transmission coil and resonating with the power transmission coil.

  The power transmission device of the present invention further includes a housing that stores the power transmission coil and visualizes a range in which the power reception device can be placed.

  Further, in the power transmission device of the present invention, the power transmission coil has a corner portion constituted by a first outer ring side and a second outer ring side, and an inductance value of the power transmission coil is determined by the inner ring of the power reception coil. It is a value based on the coupling coefficient in the case of being located near the intersection of the straight line including the first outer ring side and the straight line including the second outer ring side rather than the midpoint of one outer ring side.

  As described above, since the inductance value of the power transmission coil is a value based on the coupling coefficient when the power reception coil is located at the end of the power transmission coil, the power transmission device can transmit power to the power reception device in a wide range.

  The power transmission system of the present invention is a power transmission system that performs power transmission by electromagnetic induction, and includes a transmission circuit unit having a power transmission coil and a power reception coil formed by winding a conductor in a spiral shape, and the power transmission coil A power circuit section for supplying power to the power supply circuit, and a load circuit section for supplying power via the power receiving coil, wherein the power transmission coil and the power receiving coil have inductance values at least part of the inner ring of the power receiving coil. Is a value based on the coupling coefficient when the power transmission coil is located between the outer ring and the inner ring.

  In the power transmission system of the present invention, the inductance value of the power transmission coil is a value based on the impedance value of the transmission circuit unit viewed from the power supply circuit unit.

  In the power transmission system of the present invention, the inductance value of the power receiving coil is a value based on the impedance value of the load circuit unit.

  In the power transmission system of the present invention, the inductance value of the power transmission coil is L1, the inductance value of the power reception coil is L2, the impedance value of the transmission circuit unit viewed from the power supply circuit unit is Z1, and the load When the impedance value of the circuit unit is Z2, the coupling coefficient is K, and the frequency of power transmitted from the power transmission coil to the power reception coil is f, the relationship of 2πfL1 = Z1 / K and 2πfL2 = Z2 / K is satisfied. .

  As described above, since the inductance values of the power transmission coil and the power reception coil are values based on the coupling coefficient when the power reception coil is positioned at the end of the power transmission coil, the load circuit unit can receive power in a wide range.

  The power receiving device of the present invention is a receiving device that receives power from a power transmitting device having a power transmitting coil by electromagnetic induction, and the power is supplied through the power receiving coil that receives power from the power transmitting coil and the power receiving coil. The inductance value of the power receiving coil is a value based on the coupling coefficient when the coupling coefficient between the power receiving coil and the power transmitting coil is not maximized.

  The power transmission device of the present invention is a power transmission device that transmits electric power to the power reception device of the power reception coil by electromagnetic induction, the power transmission coil that transmits power to the power reception coil, and a power supply circuit unit that supplies power to the power transmission coil The inductance value of the power transmission coil is a value based on the coupling coefficient when the coupling coefficient between the power receiving coil and the power transmission coil is not maximized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the outline | summary of the wireless power transmission system 3 of embodiment of this invention is demonstrated using FIG. FIG. 1 is a circuit configuration diagram of a wireless power transmission system according to an embodiment of the present invention. The wireless power transmission system 3 performs power transmission wirelessly (contactlessly) from a power transmission device (charging device) 1 to an electronic device 2 such as a mobile phone, and the electronic device 2 includes mounted components (not shown). The secondary battery 4 that supplies power for operation is provided, and the secondary battery 4 is charged with the power transmitted from the power transmission device 1.

  In this wireless power transmission system 3, in order to perform power transmission by electromagnetic induction (using magnetic flux as a medium), the power transmission device 1 includes a power transmission coil (primary coil) 5, and the electronic device 2 receives a power reception coil (secondary coil). 6 is provided. When AC power is supplied to the power transmission coil 5 of the power transmission device 1, the power transmission coil 5 is magnetically coupled to the power reception coil 6 of the electronic device 2, and an AC voltage is induced in the power reception coil 6, whereby AC power is transmitted. It is transmitted from the coil 5 to the power receiving coil 6. In this embodiment, the non-contact power transmission method may be an electromagnetic induction method, a radio wave method, or an electromagnetic resonance method.

  The power transmission device 1 includes a primary transmission circuit unit 101 that transmits power to the electronic device 2 and a power supply circuit unit 102 that supplies power to the primary transmission circuit unit 101. The primary side transmission circuit unit 101 includes a power transmission coil 5 and a primary side capacitor 19 (see FIG. 2) connected in series to the power transmission coil 5. The power supply circuit unit 102 includes an AC / DC converter 11, a power transmission control unit 12, and a DC / AC inverter 13. The AC / DC converter 11 converts AC power supplied from a power source (commercial power source) 8 into DC power. The power transmission control unit 12 controls the operation of the DC / AC inverter 13. The DC / AC inverter 13 is a DC-AC converter that converts DC power sent from the AC / DC converter 11 via the power transmission control unit 12 into an AC voltage having a predetermined frequency and supplies the AC voltage to the power transmission coil 5. Note that the DC / AC inverter 13 may be replaced with a driver or the like.

  The power transmission control unit 12 includes a control circuit 14, a voltage monitoring unit 15, and a temperature monitoring unit 16. The control circuit 14 controls the operation of the DC / AC inverter 13. The voltage monitoring unit 15 monitors the voltage of AC power supplied from the DC / AC inverter 13 to the power transmission coil 5. The temperature monitoring unit 16 monitors the temperature of the power transmission coil 5. When the voltage monitoring unit 15 and the temperature monitoring unit 16 detect an abnormality in voltage and temperature, power supply to the power transmission coil 5 is stopped.

  The DC / AC inverter 13 converts the DC power sent via the AC / DC converter 11 and the power transmission control unit 12 into an AC voltage having a predetermined frequency, and supplies the AC voltage to the primary side transmission circuit unit 101.

  The electronic device 2 includes a secondary transmission circuit unit 201 that receives power from the power transmission device 1 and a load circuit unit 202 that uses power received by the secondary transmission circuit unit 201. The secondary side transmission circuit unit 201 includes a power receiving coil 6 and a secondary side capacitor 29 (see FIG. 2) connected in series with the power receiving coil 6. The load circuit unit 202 includes a power reception circuit unit 21, a power reception control unit 22, and a charge control circuit 23. The power receiving circuit unit 21 converts an alternating current induced in the power receiving coil 6 by electromagnetic induction with the power transmitting coil 5 of the power transmitting device 1 into predetermined direct current power. The power reception control unit 22 controls the operation of the power reception circuit unit 21. The charging control circuit 23 charges the secondary battery 4 by supplying electric power sent from the power receiving circuit unit 21 via the power receiving control unit 22 to the secondary battery 4.

  The power receiving circuit unit 21 includes a rectifier circuit 24 (AC / DC converter) and a regulator (DC / DC converter) 25. The rectifier circuit 24 is an AC-DC converter that converts AC power induced in the power receiving coil 6 (received by the power receiving coil 6) into DC power. The regulator 25 is a DC-DC converter that converts DC power sent from the rectifier circuit 24 into a predetermined voltage suitable for charging the secondary battery 4. The rectifier circuit 24 and the regulator 25 are an example of a power receiving side power converter.

  The power reception control unit 22 includes a control circuit 26 and a voltage monitoring unit 27. The control circuit 26 controls the operation of the power receiving circuit unit 21. The control circuit 26 controls the operation of the power receiving circuit unit 21. The voltage monitoring unit 27 monitors the voltage of AC power induced in the power receiving coil 6. In addition, the power reception control unit 22 monitors the state of the device mounted on the electronic device 2, for example, the temperature of the power receiving coil 6, the charging state of the secondary battery 4, etc. To stop.

  Moreover, in this Embodiment, the electronic device detection part 31 which detects that the electronic device 2 was mounted on the electronic device mounting surface in the power transmission apparatus 1 is provided. Based on the detection result of the electronic device detection unit 31, the power transmission operation of the power transmission device 1 is controlled. That is, when the electronic device 2 is placed on the electronic device placement surface (charging surface), supply of AC power to the power transmission coil 5 is started, and when the electronic device 2 leaves the power transmission device 1, the power transmission coil 5. Stop supplying AC power to

  In the electronic device detection unit 31, the fluctuation of the voltage value (or current value) generated in the power transmission coil 5 due to the load impedance changing due to the power receiving coil 6 of the electronic device 2 being close to the power transmission coil 5 of the power transmission device 1. Based on this, it is detected that the electronic device 2 is placed on the electronic device placement surface. At this time, the amount of change in the voltage value (or current value) of the power transmission coil 5 is compared with a preset threshold value to determine whether or not the electronic device 2 is placed on the electronic device placement surface. Just do it.

  In the present embodiment, the electronic device 2 is also provided with the power transmission device detection unit 41 that detects that it is placed on the electronic device placement surface of the power transmission device 1. Based on the detection result of the power transmission device detection unit 41, the power receiving operation of the electronic device 2 is controlled.

  In the power transmission device detection unit 41, the fluctuation of the voltage value (or current value) generated in the power reception coil 6 due to a change in load impedance caused by the power reception coil 6 of the electronic device 2 approaching the power transmission coil 5 of the power transmission device 1. Based on this, it is detected that the electronic device 2 is placed on the electronic device placement surface. At this time, the fluctuation amount of the voltage value (or current value) of the power receiving coil 6 is compared with a preset threshold value to determine whether or not the electronic device 2 is placed on the electronic device placement surface. Just do it.

  Moreover, in this Embodiment, the power transmission apparatus 1 and the electronic device 2 are each provided with the information transmission / reception parts 32 and 42, and it is required via the power transmission coil 5 and the power receiving coil 6 between the power transmission apparatus 1 and the electronic device 2. It is possible to transmit information to send and receive information. Note that this information transmission may be simple bit communication or coded communication.

  The information transmission / reception units 32 and 42 of the power transmission device 1 and the electronic device 2 have modulation / demodulation circuits 33 and 43 that perform modulation / demodulation of signals including information, respectively. In the modulation / demodulation circuits 33 and 43, the modulation signal generated by the transmission / reception modulation circuits 33 and 43 is sent to the transmission destination via the power transmission coil 5 and the power reception coil 6, and at the transmission destination, the power transmission coil 5 or the power reception coil 6. The modulation signal extracted from the output is demodulated by the modem circuits 33 and 43 to obtain transmission information.

  Here, when transmitting information from the power transmission device 1 to the electronic device 2, the modulation signal output from the information transmission / reception unit 32 is superimposed on the AC signal for power transmission by the DC / AC inverter 13, thereby simultaneously with power transmission. Information transmission can be performed. Further, information transmission may be performed when power transmission is not performed.

  Here, the information exchanged between the power transmission device 1 and the electronic device 2 is state information regarding the states of the power transmission device 1 and the electronic device 2. As the state information, for example, during charging of the secondary battery 4, information on the charging state of the secondary battery 4 is transmitted from the electronic device 2 to the power transmission device 1, and power transmission is continued when the secondary battery 4 needs to be charged. When the charging of the secondary battery 4 is completed, the power transmission is stopped. Further, as status information, information such as temperature and voltage is exchanged between the power transmission device 1 and the electronic device 2, and control is performed to stop power transmission even when the status information indicates an abnormality.

  Moreover, in this Embodiment, the power transmission apparatus 1 and the electronic device 2 are each provided with the authentication parts 34 and 44, and mutual authentication is performed between the power transmission apparatus 1 and the electronic device 2. FIG. In the power transmission device 1 and the electronic device 2, authentication information such as identification information of the power transmission device 1 and the electronic device 2 used for mutual authentication is exchanged by the information transmission / reception units 32 and 42 included in each, and based on this authentication information Authentication units 34 and 44 authenticate each other.

  This mutual authentication is performed when power transmission from the power transmission device 1 to the electronic device 2 is started. That is, when the power transmission device 1 and the electronic device 2 detect that the electronic device 2 is placed on the electronic device placement surface of the power transmission device 1, identification information is exchanged between the power transmission device 1 and the electronic device 2. And authenticate each other. When this mutual authentication is successful, power transmission from the power transmission device 1 to the electronic device 2 is started. When mutual authentication fails, power transmission is not performed.

  Next, a method for determining inductance values (hereinafter also referred to as L values) of the power transmission coil 5 and the power reception coil 6 will be described with reference to FIG.

  FIG. 2 is a conceptual diagram of a circuit configuration of the wireless power transmission system according to the embodiment of the present invention. As shown in FIG. 2, the wireless power transmission system 3 includes a power supply circuit unit 102, a transmission circuit unit 301, and a load circuit unit 202. The transmission circuit unit 301 includes the above-described primary transmission circuit unit 101 and secondary transmission circuit. Part 201.

  The primary side transmission circuit unit 101 includes a power transmission coil 5 and a primary side capacitor 19 connected in series to one end of the power transmission coil 5. And the power transmission coil 5 and the primary side capacitor | condenser 19 form a series resonance circuit.

  Similarly, the secondary-side transmission circuit unit 201 includes a power receiving coil 6 and a secondary capacitor 29 connected in series to one end of the power receiving coil 6. The power receiving coil 6 and the secondary capacitor 29 are a series resonant circuit. Form.

  To briefly explain the flow of power transmission again, the power supply circuit unit 102 is electrically connected to the power supply 8 and supplied with power from the power supply 8. The power supply circuit unit 102 is electrically connected to the primary side transmission circuit unit 101, converts the power from the power source 8 as described above, and transmits the electric power to the electronic device 2 via the primary side transmission circuit unit 101. .

  The load circuit unit 202 is electrically connected to the secondary transmission circuit unit 201 and receives the power transmitted from the power transmission device 1 via the secondary transmission circuit unit 201. Then, the load circuit unit 202 converts the received power as described above, and stores the converted power in the secondary battery 4 in the load circuit unit 202.

  In the wireless power transmission system 3 configured as described above, the impedance when viewing the transmission circuit unit 301 from the power supply circuit unit 102 is Z1, and the impedance of the load circuit unit 202 (see the load circuit unit 202 from the transmission circuit unit 301). Impedance) is Z2, the reactance of the power transmission coil 5 is X1 (= ωL1), the reactance of the power reception coil 6 is X2 (= ωL2), and the coupling coefficient (degree of coupling) between the power transmission coil 5 and the power reception coil 6 is K ( = M / √ (L1 × L2), M: mutual reactance), and transmission frequency is f (= ω / (2π)), in the present embodiment, the relationship of the following (formula 1) and (formula 2) is Fulfill.

ωL1 = Z1 / K (Formula 1)
ωL2 = Z2 / K (Formula 2)
L1 and L2 satisfying the relational expressions (Equation 1) and (Equation 2) are calculated, and the L value of the power transmission coil 5 is L1, and the L value of the power reception coil 6 is L2. C1 which is the capacitance value (hereinafter also referred to as C value or capacitance) of the primary side capacitor 19 that forms a resonance circuit with the power transmission coil 5 is based on L1 (for example, using transmission frequencies f, C1 and L1). Calculated from the resonance equation).

  By calculating L1 and L2 in this way, in the transmission circuit unit 301 including the power transmission coil 5 and the power reception coil 6 constituting the series resonant circuit, the primary side transmission circuit unit 101 and the secondary side transmission circuit unit 201 Impedance matching can be achieved. As a result, even if the place where the electronic device 2 is placed changes, the variation in the coupling coefficient between the power transmission coil 5 and the power reception coil 6 is reduced. That is, even if the position where the electronic device 2 is placed changes, the electronic device 2 can receive power.

  Since L1, L2, Z1, Z2, C1, and C2 are calculated as described above, L1 is a value based on the impedance Z1 and the coupling coefficient K, and L2 is a value based on the impedance Z2 and the coupling coefficient K. . In other words, the impedance Z1 is a value based on the L value (L1) of the power transmission coil 5 and the coupling coefficient K, and the impedance Z2 is a value based on the L value (L2) of the power receiving coil 6 and the coupling coefficient K.

  At this time, L1 and L2 are values satisfying two relational expressions (for example, (Expression 1) and (Expression 2)), and a common coupling coefficient K is used for these two relational expressions. The coupling coefficient K is a value based on L1 and L2. Therefore, L1 is a value based on the impedance Z1, the impedance Z2, and the L value (L2) of the power receiving coil 6, and L2 is a value based on the impedance Z1, the impedance Z2, and the L value (L1) of the power transmitting coil 5. is there. In other words, the impedance Z1 is a value based on the L value (L1) of the power transmission coil 5, the L value (L2) of the power receiving coil 6, and the output impedance Z2, and the impedance Z2 is the L value of the impedance Z1 and the power transmission coil 5 ( L1) and a value based on the L value (L2) of the power receiving coil 6.

  That is, from (Expression 1) and (Expression 2), L1, L2, Z1, and Z2 satisfy the (Expression 3) relationship.

Z1 / L1 = Z2 / L2 (Formula 3)
Therefore, as shown in (Equation 3), in the present embodiment, the ratio of the impedance Z1 and the L value (L1) of the power transmission coil 5 is the same as the ratio of the impedance Z2 and the L value (L2) of the power receiving coil 6. is there.

  Hereinafter, the configuration of the wireless power transmission system 3 will be described with reference to FIGS. Members having the same configuration and function are denoted by the same reference numerals, and detailed description thereof is omitted.

  3 is a perspective view of a first example of the wireless power transmission system according to the embodiment of the present invention. FIG. 4 is a top view of the first example of the wireless power transmission system according to the embodiment of the present invention. These are sectional drawings of the 1st example of the wireless power transmission system which concerns on embodiment of this invention. FIG. 5 is also a view of the cross section of FIG. 4 taken along the X axis when viewed in the Y axis direction.

  As illustrated in FIGS. 3 to 5, the power transmission device 1 includes a housing 1 a having one surface as a charging surface (electronic device placement surface) 1 b and stores the power transmission coil 5 in the housing 1 a. The electronic device 2 has a housing 2a having one surface as a charging surface 2b, and a power receiving coil 6 in the housing 2a. When the electronic device 2 is placed on the upper surface (charging surface 1 a) of the housing 1 a of the power transmission device 1, power is supplied via the power transmission coil 5 and the power reception coil 6. Of course, the electronic device 2 is preferably placed so that the plane direction of the power receiving coil 6 faces the plane direction of the power transmission coil 5.

  Moreover, as shown in FIGS. 4 and 5, the power transmission coil 5 is disposed substantially parallel to the charging surface 1b. And the power transmission coil 5 is arrange | positioned near the charging surface 1b rather than the counter electrode surface of the charging surface 1b. That is, the power transmission coil 5 is disposed near the charging surface 1b. For this reason, the distance between the power transmission coil 5 and the electronic device 2 placed on the charging surface 1a can be reduced, and the efficiency of power transmission can be increased.

  The power transmission coil 5 is a planar coil in which a conductor is spirally wound from the inside to the outside, and the power transmission coil 5 is wound on the outermost side with an inner ring (inner circumference) 5a that is a conductor wound on the innermost side. And an outer ring (outer circumference) 5b which is a turned conductor. The inner ring 5a has a polygonal shape having a plurality of inner ring side corners 5c, and similarly, the outer ring 5b has a polygonal shape having a plurality of outer ring side corners 5d. Although the inner ring side corner portion 5c and the outer ring side corner portion 5d of the present embodiment are formed in an arc shape (bow shape), it is not necessary to limit to this. Moreover, the inner side of the inner ring 5a is a hollow portion, and the conductor around the hollow portion of the power transmission coil 5 is wound.

  Similarly, the power receiving coil 6 is also arranged on the charging surface 2b side. That is, the power receiving coil 6 is disposed closer to the charging surface 2b than the counter electrode surface of the charging surface 2b. Thereby, when the electronic device 2 is mounted on the power transmission device 1, the distance between the power receiving coil 6 and the power transmission device 1 can be reduced, and the efficiency of power transmission can be increased.

  The power receiving coil 6 is a planar coil in which a conductor is spirally wound from the inside to the outside, and is wound outwardly from an inner ring (inner circumference) 6a that is a conductor wound inwardly. And an outer ring (outer periphery) 6b which is a conductor. Although the inner ring 6a and the outer ring 6b are formed in a substantially circular shape, it is not necessary to limit to this. Further, the inner side of the inner ring 6a is a hollow portion, and a conductor is wound around the hollow portion of the power receiving coil 6.

  Further, the electronic device 2 (the housing 2a thereof) has a charging range (mounting range) 105 indicating a predetermined range. The charging range 105 is a range in which the electronic device 2 can be charged, and is visualized (visualized) on the housing 2a as shown in FIG. That is, when the electronic device 2 is placed at least inside the charging range 105, the electronic device 2 can be charged. In this way, the charging range 105 is visualized in the housing 2a, so that it is possible to tell the user where to place the electronic device 2.

  Note that the charging range 105 may be visualized in any way. In the present embodiment, the housing 2a and the charging range 105 are separated in color, but the charging range 105 may be visualized by a depression or the like of the housing 2a. That is, the housing 1a may be formed such that the charging range 105 is uneven with respect to the charging surface 1a.

  Further, in the present embodiment, in FIG. 5, when the center of power receiving coil 6 is inside charging range 105, electronic device 2 is assumed to be inside charging range 105. However, the present invention is not limited to this. When all of the power receiving coil 5 (or electronic device 2) is inside the charging range 105, or at least a part of the power receiving coil 5 (or electronic device 2) is within the charging range 105. When it is above, the electronic device 2 may be inside the charging range 105 (that is, the electronic device 2 can be charged).

  Next, characteristics of the wireless power transmission system 3 according to the present embodiment will be described with reference to FIGS.

  FIG. 6 is a diagram for explaining the positional relationship between the power transmitting coil and the power receiving coil according to the embodiment of the present invention, and FIG. 7 is the relationship between the coupling coefficient and the position of the power receiving coil according to the embodiment of the present invention. FIG. 8 is a diagram showing the relationship between the output voltage and the position of the power receiving coil according to the embodiment of the present invention. In FIG. 6, the casing 2 a is omitted in order to clearly show the positional relationship between the power transmission coil 5 and the power reception coil 6.

  FIG. 6 shows a case where the power receiving coil 6 is placed at positions A to C, respectively. Assuming that the intersection of the X axis and the Y axis is the center of the power transmission coil 5, the position A is when the center of the power reception coil 6 is located at the center of the power transmission coil 5. The position B is when the power receiving coil 6 is moved from the position A to the charging range 105 in the X-axis direction (from X0 to X1). That is, position B is when the center of the power receiving coil is located at the intersection of the X axis and the charging range. Further, the position C is when the center of the power receiving coil 6 is located at a point that becomes the corner of the charging range 105.

  Although the details will be described later, the L value (L1) of the power transmission coil 5 and the L value (L2) of the power reception coil 6 are the coupling coefficient K when the power reception coil 6 is located at the position C and the above relational expressions (1), ( 2). FIG. 7 shows the transition of the coupling coefficient K that changes based on the positional relationship between the power transmission coil 5 and the power reception coil 6 at this time. FIG. 8 shows the transition of the voltage (hereinafter also referred to as output voltage E) output to the regulator 25 by the rectifier circuit 24 that changes based on the positional relationship between the power transmission coil 5 and the power reception coil 6.

  FIG. 7 is a graph in which the vertical axis represents the coupling coefficient K and the horizontal axis represents the position of the power receiving coil 6 with respect to the power transmission coil 5 (the shift amount of the secondary coil in the X-axis direction). That is, FIG. 7 shows the amount of change (transition) of the coupling coefficient K when the electronic device 2 is moved from the center of the power transmission coil 5 (intersection of the X axis and Y axis in FIG. 6) in the X axis direction (up to X1). Show. As can be seen from FIG. 7, when the power receiving coil 6 is near the center of the power transmission coil 5, a high coupling coefficient K can be maintained, but when the power receiving coil 6 approaches the end of the power transmission coil 5, the coupling coefficient K rapidly decreases. To do.

  FIG. 8 shows a phenomenon similar to the graph of FIG. FIG. 8 is a graph in which the vertical axis represents the output voltage E and the horizontal axis represents the position of the power receiving coil 6 relative to the power transmission coil 5 (the shift amount of the secondary coil in the X-axis direction). That is, FIG. 8 shows the change amount (transition) of the output voltage E (input voltage of the regulator 25) when the electronic device 2 is moved from the center of the power transmission coil 5 in the X-axis direction (up to X1).

  As can be seen with reference to FIGS. 7 and 8, the coupling coefficient K and the output voltage E of the rectifier circuit 24 show the same change tendency, and rapidly decrease when the power receiving coil 6 approaches the end of the power transmitting coil 5. In other words, the higher the coupling coefficient K, the higher the efficiency of power transmission (the rectifier circuit 24 can increase the output voltage E).

  Although not shown, the above-described tendency of the coupling coefficient K and the output voltage E shows the same tendency when the power receiving coil 6 is moved in the Y-axis direction. From the above, the coupling coefficient K and the output voltage E become smaller as the power receiving coil 6 approaches the end of the power transmission coil 5 (as it moves away from the center of the power transmission coil 5). Therefore, in the charging range 105 of the present embodiment, the coupling coefficient K and the output voltage E decrease in the order of position A, position B, and position C.

  Next, characteristic points of the present embodiment will be described in detail.

  In the following description, when the power receiving coil 6 is placed in the charging range 105, the coupling coefficient between the power transmitting coil 5 and the power receiving coil 6 (or the output voltage E of the rectifier circuit 24) is minimized. Kmin. In the present embodiment, the coupling coefficient when the center portion of the power receiving coil 6 is located at the corner of the charging range 105, that is, when the power receiving coil 6 is located at the position C, is Kmin. Further, the output voltage of the rectifier circuit 24 when the power receiving coil 6 is located at the position C is Emin.

  In the following description, when the power receiving coil 6 is placed in the charging range 105, the coupling coefficient between the power transmitting coil 5 and the power receiving coil 6 (or the output voltage E of the rectifier circuit 24) becomes maximum. Is Kmax. In the present embodiment, the coupling coefficient when the center portion of power receiving coil 6 is located near the center portion of charging range 105 (or power transmission coil 5) is Kmax. Further, the output voltage of the rectifier circuit 24 when the power receiving coil 6 is located at the position where the coupling coefficient Kmax is set to Emax.

  When the power transmission coil 5 is formed of a flat coil as in the present embodiment, the magnetic flux intensity of the power transmission coil 5 tends to be strong on the inside and weak on the outside. As described above, the coupling coefficient K tends to be strong when the power receiving coil 6 is located at the center of the power transmitting coil 5 and weak when the power receiving coil 6 is located outside the power transmitting coil 5.

  For this reason, when the power receiving coil 6 is located at the end of the power transmitting coil 5, the magnetic coupling is lowered and the transmission efficiency is lowered, so that it is difficult for the electronic device 2 to receive power.

  Therefore, in the present embodiment, when calculating the L value (L1) of the power transmission coil 5 and the L value (L2) of the power receiving coil 6 using the relational expressions (1) and (2), the coupling coefficient Kmin is Used. That is, L1 and L2 are values based on the coupling coefficient Kmin.

  Thereby, the transmission efficiency when the power receiving coil 6 is located at the end (for example, position C) of the power transmitting coil 5 can be improved. That is, the output voltage Emin can be increased, and the electronic device 2 can receive power even when the power receiving coil 6 is located at the end of the power transmitting coil 5.

  When L1 and L2 are values based on the coupling coefficient Kmin, the transmission efficiency when the power receiving coil 6 is located near the center of the power transmission coil 5 is reduced, but the magnetic flux generated by the power transmission coil 5 is strong. Even when the power receiving coil 6 is located at the center of the power transmitting coil 5, the electronic device 2 can receive power.

  Therefore, the electronic device 2 can receive power not only when the power receiving coil 6 is positioned at the center of the power transmitting coil 5 but also when it is positioned at the end where the generated magnetic flux is weak. That is, the range in which the electronic device 2 can receive power can be increased.

  Further, in the present embodiment, the outer ring 5b of the power transmission coil 5 is larger than the outer ring 6b of the power reception coil 6, and therefore the power transmission coil 5 can generate a magnetic field in a wide range. That is, the electronic device 2 can receive power over a wide range.

  From the above, L1 and L2 are values based on the coupling coefficient K when the power receiving coil 6 is located at the end of the power transmitting coil 5, but when the power receiving coil 6 is located at the end of the power transmitting coil 5 here, at least the power receiving This is when the coil 6 is positioned closer to the outer ring of the power transmission coil 5 than the center of the power transmission coil 5 (intersection of the X axis and the Y axis).

  In general, when the hollow portion of the power transmission coil 5 and the hollow portion of the power reception coil 6 overlap (for example, when the power reception coil 6 is located at the position A), the magnetic coupling becomes high, that is, the coupling coefficient K is 1. Get closer to. In other words, when one hollow part does not include the other hollow part among the hollow part of the power transmission coil 5 and the hollow part of the power receiving coil 6, the coupling coefficient K tends to decrease and the transmission efficiency tends to decrease. Accordingly, L1 and L2 are calculated based on the coupling coefficient K when at least a part of the power receiving coil 6 is located between the inner ring 5a and the outer ring 5b or on the conductor of the power transmitting coil 5. Thereby, the transmission efficiency when the power receiving coil 6 is located at the end of the power transmitting coil 5 can be increased, and the electronic device 2 can receive power in a wide range.

  Further, as shown in FIG. 8, the output voltage E rapidly decreases when the power receiving coil 6 is positioned in the vicinity of the outer ring 5 b of the power transmission coil 5, so that the center of the power receiving coil 6 is L1 and L2 of the power transmission coil 5. A value based on the coupling coefficient K when located closer to the outer ring 5b than to the inner ring 5a is more preferable.

  Therefore, L1 and L2 may be calculated based on the coupling coefficient K when the power receiving coil 6 is positioned at the position B, or calculated based on the coupling coefficient K when the power receiving coil 6 is positioned at the position C. Also good.

  Of course, in the case of the present embodiment, the coupling coefficient K is minimized within the charging range 105 when the power receiving coil 6 is located at the position C. Therefore, L1 and L2 are the values when the power receiving coil 6 is located at the position C It is preferable to calculate based on the coupling coefficient K (Kmin). That is, when the power transmission coil 5 has a polygonal shape having a plurality of outer ring side corners 5d as in the present embodiment, L1 and L2 are obtained when the power receiving coil 6 is close to the outer ring side corner 5d of the power transmission coil 5. A value based on the coupling coefficient K is preferable.

  Here, the power receiving coil 6 is close to the outer ring side corner 5d of the power transmission coil 5 when the power receiving coil 6 is located closer to the outer ring side corner 5d than the center point of the power transmission coil 5, more preferably. This is a case where the power receiving coil 6 is located closer to the outer ring side corner 5d than the inner ring side corner 5c of the power transmission coil. Alternatively, when the outer ring side corner is composed of the outer ring sides 5e and 5f, the inner ring 6a of the power receiving coil 6 includes a straight line including the outer ring side 5e and the outer ring side 5f from the midpoint of the outer ring side 5e (or the outer ring side 5f). L1 and L2 may be calculated based on the coupling coefficient K in the case of being located near the intersection 7 of the straight line including.

  Further, as described above, the regulator 25 converts the DC voltage input through the rectifier circuit 24 into a predetermined DC voltage and outputs it. Input voltage range). For example, when the input voltage range of the regulator 25 is 8 to 32V and the output voltage is 9V, the regulator 25 can output 15V DC voltage by converting it to 9V, but it outputs 9V DC voltage from 3V DC voltage. It is difficult to do. In addition, the regulator 25 having a large input voltage range is costly and causes an increase in the cost of the electronic device 2.

  However, in the present embodiment, L1 and L2 are calculated using the coupling coefficient Kmin, so that an increase in cost of the electronic device 2 can be suppressed. More specifically, in this embodiment, the transmission efficiency when the power receiving coil 6 is located at the end of the power transmission coil 5 is high, and the transmission efficiency when the power receiving coil 6 is located at the center of the power transmission coil 5 is high. Lower. That is, the output voltage Emax can be reduced and the output voltage Emin can be increased. In other words, the range of the DC voltage input to the regulator 25 can be reduced. Therefore, it is not necessary to mount the regulator 25 having a large input voltage range on the electronic device 2, and the cost increase of the electronic device 2 can be suppressed.

  In the present embodiment, the regulator 25 has an input voltage range. The lower limit value of the input voltage range is equal to or lower than the output voltage Emin, and the upper limit value is equal to or higher than the output voltage Emax. Accordingly, the secondary battery 4 can be charged wherever the power receiving coil 6 is placed within the charging range 105.

  Next, a comparative example for the present embodiment will be described with reference to FIG.

  FIG. 9 is a diagram illustrating a relationship between the output voltage and the position of the power receiving coil according to the comparative example. In the comparative example, the calculation method of the L value of the power transmission coil 5 and the power reception coil 6 is different, and L1 and L2 are not values based on the coupling coefficient Kmin, but the relation coefficient and the coupling coefficient K when the power reception coil 6 is located at the position A. This is a value calculated using (1) and (2). The transition of the output voltage E at this time is shown in FIG.

  8 and 9 are compared, at the position A, the output voltage E higher in the graph shown in FIG. 9 is measured. However, in the comparative example shown in FIG. 9, at position B, the electronic device 2 is not supplied with sufficient power, and the rectifier circuit 24 cannot output a DC voltage. That is, when L1 and L2 are calculated as in the comparative example, the electronic device 2 cannot receive power at the end of the power transmission coil 5, and the chargeable range is limited.

  From the above, by calculating L1 and L2 suitable for the coupling coefficient when the power receiving coil 6 is located at the end of the power transmitting coil 5, the range in which the electronic device 2 can receive power can be widened. That is, even when the power receiving coil 6 is located at the end of the power transmitting coil 5, the rectifier circuit 24 can output a DC voltage and can receive the secondary battery 4.

  Hereinafter, supplementary items in the above-described embodiment will be described.

  As shown in FIGS. 8 and 9, the output voltage E rapidly decreases when the power receiving coil 6 is positioned near the outer ring 5 b of the power transmission coil 5. It is more preferable that the value be based on the coupling coefficient K when approaching the outer ring 5b. Thereby, even when the power receiving coil 6 is located near the outer ring of the power transmitting coil 5, the regulator 25 can output the DC voltage more reliably, that is, can supply power to the secondary battery 4.

  Further, the shapes and types of the power transmission coil 5 and the power reception coil 6 are not particularly limited. That is, the power transmission coil 5 and the power reception coil 6 may be circular or polygonal, and may be a planar coil or a multilayer coil. Further, the power transmission device 1 and the electronic device 2 may not be a rectangular parallelepiped as in the present embodiment, and the charging surfaces 1b and 2b may not be flat.

  Moreover, in this Embodiment, L1 and L2 were calculated using the coupling coefficient K when the receiving coil 6 is located in the edge part of the power transmission coil 5 on the relationship of transition of the coupling coefficient K shown in FIG. When the power receiving coil 6 is positioned at the center of the power transmitting coil, if the coupling coefficient K tends to decrease, L1 and L2 may be calculated using the coupling coefficient K at this time. That is, the coupling coefficient K used when calculating L1 and L2 only needs to be at least other than the coupling coefficient Kmax. In other words, L1 and L2 are values based on the coupling coefficient K other than the coupling coefficient Kmax.

  Alternatively, L1 and L2 may be calculated using the coupling coefficient K when the power receiving coil 6 is positioned outside the outer ring 5b of the power transmitting coil 5. When the power transmission coil 5 generates a strong magnetic field, the charging range 105 may be configured to be larger than the outer ring 5b of the power transmission coil 5.

  Moreover, as shown in FIG. 10, the power transmission apparatus 1 may be installed vertically. FIG. 10 is a perspective view of a second example of the wireless power transmission system according to the embodiment of the present invention. In FIG. 10, the electronic device 2 and the housing 2b are omitted, and only the power receiving coil 6 is disclosed.

  As shown in FIG. 10, in the case of the second example, the housing 1 a of the power transmission device 1 includes two electronic device boxes 1 c for holding the electronic device 2. The electronic device 2 is fixed to the side surface of the power transmission device 1 by being inserted into the electronic device box 1c. Thereby, even when the power transmission device 1 is placed vertically, the electronic device 2 can be disposed in the vicinity of the power transmission device 1, and the electronic device 2 can receive power.

  The housing 1a may be provided with three or more electronic device boxes 1c, and the electronic device boxes 1c may be provided on both sides as shown in FIG. A plurality of electronic devices 2 may be inserted into one electronic device box 1c.

  Further, as in the first example, when the electronic device 2 is placed on the upper surface of the power transmission device 1, the power transmission device 1 may be configured by a desk. That is, the secondary-side transmission circuit unit 201 and the load circuit unit 202 are provided in the desk, and the user simply charges the electronic device 2 (mobile terminal, PC, etc.) on the desk to charge the electronic device 2. Thereby, even for a long-time meeting or the like, the electronic device 2 can be operated without being connected to the power cable, and the convenience system can be improved.

  The present invention is applicable to a power transmission device that transmits power via a power transmission coil, a power reception device that receives power via a power reception coil, and a power transmission system including a power transmission device and a power reception device.

DESCRIPTION OF SYMBOLS 1 Power transmission apparatus 2 Electronic device 3 Wireless power transmission system 4 Secondary battery 5 Power transmission coil 5a Inner ring 5b Outer ring 5c Inner ring side corner 5d Outer ring side corner 5e Outer ring side 5f Outer ring side 6 Power receiving coil 6a Inner ring 6b Outer ring 7 Intersection 8 Power supply 11 AC / DC converter 12 Power transmission control unit 13 DC / AC inverter 14 Control circuit 15 Voltage monitoring unit 16 Temperature monitoring unit 19 Primary side capacitor 21 Power receiving circuit unit 22 Power receiving control unit 23 Charge control circuit 24 Rectifier circuit 25 Regulator 26 Control circuit 27 Voltage monitoring unit 29 Secondary side capacitor 31 Electronic device detection unit 32 Information transmission / reception unit 33 Modulation / demodulation circuit 34 Authentication unit 41 Power transmission device detection unit 42 Information transmission / reception unit 43 Modulation / demodulation circuit 44 Authentication unit 101 Primary side transmission circuit unit 102 Power supply circuit unit 105 Charging range 201 Secondary transmission circuit 20 A load circuit section 301 transmission circuit unit

Claims (14)

A receiving device that receives power by electromagnetic induction from a power transmission device having a power transmission coil formed by winding a conductor in a spiral shape,
A power receiving coil formed by winding a conductor in a spiral;
A load circuit unit to which electric power is supplied through the power receiving coil,
The power receiving device is characterized in that the inductance value of the power receiving coil is a value based on a coupling coefficient when at least a part of the inner ring of the power receiving coil is located between the inner ring and the outer ring of the power transmitting coil. The power receiving device according to claim 1,
The power receiving device according to claim 1, wherein an inductance value of the power receiving coil is a value based on an impedance value of the load circuit unit. The power receiving device according to claim 2,
The power receiving device further comprising a capacitor connected in series to the power receiving coil and resonating with the power receiving coil. The power receiving device according to claim 1,
The power receiving device is characterized in that the inductance value of the power receiving coil is a value based on a coupling coefficient when the power receiving coil is positioned closer to the outer ring of the power transmitting coil than the inner ring of the power transmitting coil. A power transmission device that transmits power by electromagnetic induction to a power reception device having a power reception coil formed by winding a conductor in a spiral shape,
A power transmission coil formed by winding a conductor spirally;
A power supply circuit section for supplying power to the power transmission coil,
The power transmission apparatus according to claim 1, wherein the inductance value of the power transmission coil is a value based on a coupling coefficient when at least a part of the inner ring of the power reception coil is located between the inner ring and the outer ring of the power transmission coil. The power transmission device according to claim 5,
A power transmission device further comprising a capacitor connected in series to the power transmission coil and resonating with the power transmission coil. The power transmission device according to claim 5,
The power transmission device further includes a housing that stores the power transmission coil and visualizes a range in which the power reception device can be placed. The power transmission device according to claim 5,
The power transmission coil has a corner portion composed of a first outer ring side and a second outer ring side,
The inductance value of the power transmission coil is such that the inner ring of the power receiving coil is located closer to the intersection of the straight line including the first outer ring side and the straight line including the second outer ring side than the midpoint of the first outer ring side. A power transmission device having a value based on a coupling coefficient in the case of performing. A power transmission system that transmits power by electromagnetic induction,
A transmission circuit unit having a power transmission coil and a power reception coil formed by winding a conductor in a spiral shape;
A power supply circuit unit for supplying power to the power transmission coil;
A load circuit unit to which electric power is supplied through the power receiving coil,
The inductance value of the power transmission coil and the power reception coil is a value based on a coupling coefficient when at least a part of the inner ring of the power reception coil is located between the outer ring and the inner ring of the power transmission coil. Power transmission system. The power transmission system according to claim 9,
The power transmission system according to claim 1, wherein an inductance value of the power transmission coil is a value based on an impedance value of the transmission circuit unit viewed from the power supply circuit unit. The power transmission system according to claim 10,
The power transmission system according to claim 1, wherein an inductance value of the power receiving coil is a value based on an impedance value of the load circuit unit. The power transmission system according to claim 12,
The inductance value of the power transmission coil is L1,
The inductance value of the power receiving coil is L2,
The impedance value of the transmission circuit unit viewed from the power supply circuit unit is Z1,
The impedance value of the load circuit unit is Z2,
The coupling coefficient is K,
When the frequency of power transmitted from the power transmission coil to the power reception coil is f,
A power transmission system satisfying a relationship of 2πfL1 = Z1 / K and 2πfL2 = Z2 / K. A receiving device that receives power by electromagnetic induction from a power transmission device having a power transmission coil,
A power receiving coil that receives power from the power transmitting coil;
A load circuit unit to which electric power is supplied through the power receiving coil,
The power receiving device according to claim 1, wherein the inductance value of the power receiving coil is a value based on a coupling coefficient when a coupling coefficient between the power receiving coil and the power transmitting coil is not maximized. A power transmission device that transmits power by electromagnetic induction to a power reception device of a power reception coil,
A power transmission coil for transmitting power to the power reception coil;
A power supply circuit section for supplying power to the power transmission coil,
An inductance value of the power transmission coil is a value based on a coupling coefficient when a coupling coefficient between the power receiving coil and the power transmission coil is not maximized.