JP2015039249A - Wireless power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless power transmission device of a novel system, which is capable of eliminating the weak points of an electromagnetic induction system and an electromagnetic resonance system and extending a power transmission distance in a similar manner to the electromagnetic resonance system.SOLUTION: The wireless power transmission device includes: a transmitter unit including a transmission coil connected to a power supply section; and a receiver unit including a reception coil connected to a load section, so as to transmit the power of the power supply section to the load section through both coils in a wireless manner. The transmitter unit includes a capacitive element connected in series to the transmission coil, so as to transmit the power from the power supply section to the load section according to the leakage inductance of the transmission coil, the capacitance of the capacitive element, the leakage inductance of the reception coil, and the mutual inductance between the transmission coil and the reception coil.

Description

  The present invention relates to a wireless power transmission apparatus that wirelessly transmits power.

  Wireless power transmission for transmitting power wirelessly has been performed for notebook PCs, pocket PCs, portable terminals, and other various devices and apparatuses.

  Such wireless power transmission is conventionally performed by an electromagnetic induction method.

  This electromagnetic induction system transmits power by electromagnetic coupling between a transmission coil and a reception coil (see Patent Document 1).

  An electromagnetic induction type wireless power transmission apparatus will be described with reference to FIG. 9. 1 is a power supply unit having a power supply Vg, 3 is a transmission unit having a transmission coil L1, and 5 is a reception coil L2 and a capacitive element in parallel therewith. A receiving unit 7 having C2 is a load unit by a resistor R.

  In the wireless power transmission device of FIG. 9, an electromagnetic field generated in the transmission coil L <b> 1 is guided to the reception coil L <b> 2 and power is transmitted to the load unit 7. Here, the capacitive element C2 of the receiving unit 5 is for obtaining a large induced electromotive force in the receiving coil L2.

  However, in the electromagnetic induction type wireless power transmission device shown in FIG. 9, the transmission coil L1 and the reception coil L2 need to be aligned, so that power transmission can be performed only at a considerably close distance.

  In 2006, MIT (Massachusetts Institute of Technology) announced a system for wirelessly transmitting power by electromagnetic resonance.

  The electromagnetic resonance system has a configuration in which capacitive elements are connected in series to both a transmission coil and a reception coil, and each includes an LC resonator.

  In this electromagnetic resonance method, electric power is transmitted using a near field (evanescent field) in which an electrostatic magnetic field is dominant. In the near field, the pair of LC resonators are connected to the same natural frequency. The electromagnetic field energy generated by each LC resonator is resonated by this operation, whereby electric power is transmitted from the transmission coil to the reception coil (see Patent Document 2).

  The wireless power transmission device using this electromagnetic resonance system will be described with reference to FIG. 10. 1 is a power supply unit having a power supply Vg, 3a is a transmission unit that constitutes an LC resonator with the leakage inductance of the capacitive element C1a and the transmission coil L1a. Reference numeral 5a denotes a receiving unit that constitutes an LC resonator by the leakage inductance of the capacitive element C2a and the receiving coil L2a, and 7 denotes a load unit by a resistor R.

  In the transmission unit 3a, the capacitive element C1a and the leakage inductance of the transmission coil L1a resonate in series, thereby generating an electromagnetic field that vibrates corresponding to the resonance frequency around the transmission coil L1a. In the receiving unit 5a, current flows through the receiving coil L2a upon receiving the electromagnetic field. At this time, in the receiving unit 5a, the leakage inductance of the receiving coil L2a and the capacitive element C2a constitute a series resonance circuit. Since this resonance frequency is equal to the frequency of the electromagnetic field, the receiving unit 4a resonates. The current of the same frequency will also flow. Thereby, electric power is transmitted to the load unit 7. The resonance frequency of this electromagnetic resonance method is about 10 MHz, which is a higher frequency region than the electromagnetic induction method.

The wireless power transmission device shown in FIG. 10 can be represented by the equivalent circuit shown in FIG. Here, the inductance of the power supply unit 1, the wiring inductance on the transmission side and the reception side, and the inductance of the load unit 7 are ignored. In FIG. 11, L _e1 is a leakage inductance in the transmission unit 3a, L _e2 is a leakage inductance in the reception unit 5a, L ′ _e2 is a leakage inductance converted from the leakage inductance L _e2 to the transmission side (as viewed from the transmission side), M is the mutual inductance on the transmission side, and when the mutual inductance on the reception side is converted to the transmission side, it is also M. C2, the capacitance C _2, C ₂ 'is the capacitance obtained by converting the capacitance C ₂ of the capacitor C2a on the transmission side of the capacitor C2a, R is the resistance of the load unit 7, R'is a resistance R of the load section 7 to the transmitting side The converted resistance, R2 is a resistance on the reception side, and R2 ′ is a resistance converted from the resistance R2 on the reception side to the transmission side. These leakage inductances converted to the transmission side may be referred to as transmission-side conversion leakage inductances.

The mutual inductances M ₁ and M ₂ of the transmission coil L1a and the reception coil L2a can be obtained from the respective self-inductances L ₁ and L ₂ and the coupling coefficient k. Considering this coupling coefficient k, assuming that the coil turns ratio between the transmitting side and the receiving side is equivalent to n / k: 1, L ′ _e2 = (n / k) ² · L _e2 , C ₂ ′ = C ₂ / (n / k) ² , R ′ = (n / k) ² · R, R ₂ ′ = n / k) ² · R ₂ . Further, by this conversion, the mutual inductance M ₂ on the reception side becomes the mutual inductance M ₁ on the transmission side, where M = (M ₁ · M ₂ ) ^1/2 = k (L ₁ · L ₂ ) ^1/2 .

In the wireless power transmission device represented by such an equivalent circuit, the leakage inductance L _e1 in the transmission unit 3a and the capacitance C _{1 of the} capacitor C1a resonate, and the converted leakage inductance L ′ _e2 in the reception unit 5a and the transmission of the capacitor C2a. The side conversion capacitor C ₂ ′ resonates and power transmission is performed.

  In such a wireless power transmission device using the electromagnetic resonance method, the power transmission efficiency is lower than that of the electromagnetic induction method, but there is an advantage that the power transmission distance can be extended.

Japanese Patent Laid-Open No. 10-145987 JP 2010-267917 A

However, in the conventional electromagnetic resonance type wireless power transmission device, both the transmission unit 3a and the reception unit 5a require the capacitive elements C1 and C2, but the positional relationship between the transmission unit 3a and the reception unit 5a changes. Then, since the leakage inductance L _e1 and the converted leakage inductance L ′ _e2 change, the capacitance setting in the capacitive elements C1 and C2 for electromagnetic resonance is not always easy.

  The present invention has been made in view of the above, and can control the position by controlling the voltage, current, power, and frequency of the power supply even if the positional relationship between the transmission coil and the reception coil, which is a drawback of the electromagnetic induction system, changes. A new type of wireless power transmission device that can cope with misalignment and eliminates the difficulty of setting wireless power transmission, which is a drawback of the electromagnetic resonance method, and can extend the distance of power transmission in the same way as the electromagnetic resonance method. It is to provide.

  A wireless power transmission device according to the present invention includes a power supply unit having a function of controlling an amplitude and frequency of output voltage, output current, or output power, a transmission unit including a transmission coil connected to the power supply unit, and the transmission coil A receiving unit including a receiving coil arranged at an interval between the receiving unit and a load unit connected to the receiving unit, wherein the power of the power supply unit is transmitted to the load unit side through the two coils. A resonance circuit is configured by connecting a capacitor to any one of the power supply unit, the transmission unit, and the reception unit, and the resonance circuit is controlled by controlling the frequency in the power supply unit. The power transmission is performed.

  The load section is not limited to a resistor, and includes a rectifier circuit, a capacitor connected to the DC output side of the rectifier circuit, a resistor, and the like, as well as other load circuits.

  The transmission unit is not limited to being configured with a transmission coil, and includes wiring inductance and the like.

  The receiving unit is not limited to a receiving coil, and includes a wiring inductance.

  Preferably, in addition to controlling the frequency in the power supply unit to cause the resonance circuit to resonate, the power is transmitted by controlling the amplitude of the output voltage, output current, or output power. Is preferred.

  Preferably, the resonance circuit includes a series connection body of a transmission coil of the transmission unit and a capacitor connected in series to the transmission coil.

  Preferably, the resonance circuit includes a series connection body of a reception coil of the reception unit and a capacitor connected in series to the reception coil.

  Preferably, the resonance circuit is configured by a serial connection body of an inductance and a capacitor of the power supply unit, and the capacitor is connected in parallel to the transmission coil.

  Preferably, the inductance that determines the resonance frequency of the resonance circuit includes a wiring inductance.

  Preferably, a ferromagnetic material is disposed in the vicinity of the transmission coil and the reception coil.

  In addition, although said power supply part, a transmission coil, a receiving coil, each capacitor | condenser, and each wiring inductance have resistance, it is not mentioned in this specification.

Preferably, the expressed by an equivalent circuit of the transmitter coil and the receiver coil and the leakage inductance and mutual inductance, and the inductance Lg of the power supply unit, and the transmitting-side wiring inductance L _w1, the combined inductance of the leakage inductance L _e1 transmission coils L ₁ , the combined inductance L ₂ of the receiving coil leakage inductance Le ₂ , the receiving side wiring inductance L _w2, and the load portion inductance L _r converted to the transmitting side, L ′ ₂ , viewed from the transmitting side When the mutual inductance between the transmission coil and the reception coil is M, the following expression (1) is satisfied with respect to the frequency f of the power supply unit.

f = 1 / 2π [C ₁ [L ₁ + (L ′ ₂ · M) / (L ′ ₂ + M)]] ^1/2
The load unit is constituted by, for example, resistors, the value of the resistance as well as the R, and the resistance value R was converted to the sender resistor R', and the leakage inductance L _e2 of the reception coil _L'e2 As the leakage inductance converted to the transmission side, the value of [R ′ / [ω ² (L ′ _e2 ) ² + (R ′) ² ] ^1/2 is about 0.7 or more, that is, R ′ ≧ ω · L ′. _By setting it to _e2 , electric power can be transmitted by setting the voltage across the mutual inductance to the same level as the voltage across the load.

  In the present invention, the capacitive element is connected in series to the transmission coil in the transmission unit, but the capacitive element is connected in series to the reception coil on the reception unit side without connecting the capacitive element to the transmission coil. A resonance circuit may be configured by a receiving coil and a capacitive element in series on the receiving coil, and power may be transmitted from the transmission unit to the reception unit by the resonance circuit.

  Further, a resonance circuit may be configured by connecting a series connection body of an inductance and a capacitor to the power supply unit and connecting a transmission coil to the capacitor.

  Furthermore, you may comprise a load part with the parallel circuit of a rectifier circuit, a capacitor | condenser, and resistance.

  In the present invention, the inductance of the power supply unit, the transmission side wiring inductance, the transmission coil leakage inductance, the mutual inductance of the transmission coil and the reception coil, the capacitance by the capacitive element, the leakage inductance of the reception coil, the reception side wiring inductance, and the load unit inductance The frequency of the power supply unit is controlled so as to resonate, and the voltage of the power supply unit or the amplitude of the current or power is controlled so that the output terminal of the receiving coil, that is, the voltage of the load unit becomes a desired value. is there.

  In this case, when considering an equivalent circuit in which the transmission coil and the reception coil are divided into leakage inductance and mutual inductance and the mutual inductance of the reception coil is converted into the mutual inductance of the transmission coil, the voltage drop at the mutual inductance in the voltage vector is This is a combination of the voltage drop between the leakage inductance of the receiving coil and the receiving side wiring inductance and the voltage drop at the load. The voltage drop of the mutual inductance is roughly equal to the load voltage drop, and the mutual inductance of the receiver. The electric power can be transmitted to the load unit by causing a current to flow through the load unit.

  As described above, in the present invention, the inductance of the power supply unit, the transmission side wiring inductance, the transmission coil leakage inductance, the transmission coil and the reception coil mutual inductance, the capacitance of the capacitive element, the reception coil leakage inductance, the reception side wiring inductance, the load By controlling the frequency of the power supply part so that the part inductance resonates, it is possible to transmit power to the load part, and by connecting a capacitive element to each of the transmission side and the reception side required for conventional electromagnetic resonance. It is no longer necessary to configure a resonant circuit, making it easy to set up power transmission.

FIG. 1 is a model diagram of a wireless power transmission device according to an embodiment of the present invention. FIG. 2 is a model diagram in the case of considering the power source inductance, the wiring inductance, and the load inductance in the apparatus of FIG. FIG. 3 is an equivalent circuit diagram viewed from the transmission side of FIG. FIG. 4 is a diagram showing vector synthesis of the voltage between the reception side leakage inductance and the reception side wiring inductance and the voltage across the load section with respect to the voltage between the mutual inductances. FIG. 5 is a diagram illustrating resonance characteristics between the transmission-side power and the reception-side power. FIG. 6 is a model diagram of a wireless power transmission device according to another embodiment of the present invention. FIG. 7 is a model diagram of a wireless power transmission apparatus according to still another embodiment of the present invention. FIG. 8 is a model diagram of a wireless power transmission apparatus according to still another embodiment of the present invention. FIG. 9 is a schematic diagram of an electromagnetic induction wireless power transmission device. FIG. 10 is a schematic diagram of an electromagnetic resonance wireless power transmission device. FIG. 11 is an equivalent circuit diagram seen from the transmission side of FIG.

  Hereinafter, a wireless power transmission device according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  Referring to FIG. 1, this apparatus includes a power supply unit 1 having a power supply Vg as a power transmission source, a transmission unit 3b including a capacitive element C1b and a transmission coil L1b, and a reception unit 5b having a reception coil L2b. And a load unit 7 as a power transmission destination. The power supply unit 1 has a function of controlling the amplitude and frequency of the output voltage or output voltage or output power.

  This wireless power transmission apparatus is schematically shown in FIG. The transmission unit 3b and the reception unit 5b are arranged at an interval. The power from the power supply unit 1 is transmitted from the transmission unit 3b, received by the reception unit 5b, and transmitted to the load unit 7.

  In the embodiment, the load unit 7 is indicated by a resistor R, but is not limited thereto. Although the transmission unit 3b has a single capacitor C1b, the transmission unit 3b is not limited to a single unit, and the form thereof may be connected in series to the transmission coil L1b. The transmission unit 3b is connected to the power supply unit 1 in series. Unlike the existing electromagnetic resonance type wireless power transmission apparatus, the receiving unit 5b does not have a capacitor connected in series to the receiving coil L2b.

FIG. 1 is a model diagram that does not consider the inductance of the power supply unit 1, its resistance, the wiring inductance on the transmission side, its resistance, the inductance of the load unit 7, and its resistance. On the other hand, FIG. 2 is a model diagram in consideration of the inductance Lg of the power supply unit 1, the inductance L _{w1 of} the transmission side wiring, the inductance L _w2 of the reception side wiring, and the inductance Lr of the load unit 7. In this figure, the resistance of the power supply unit 1, the resistance of the wiring inductance on the transmission side, and the resistance of the inductance of the load unit 7 are not considered.

In the wireless power transmission device of the embodiment, the capacitance C _{1 of the} capacitor C1b, the inductance Lg of the power supply unit 1, the transmission-side wiring inductance L _w1 , the leakage inductance of the transmission coil L1b, the mutual inductance of the transmission coil L1b and the reception coil L2b, the reception coil The frequency of the power supply unit 1 is controlled so that the leakage inductance of L2b, the reception side wiring inductance _Lw2 , and the inductance Lr of the load unit 7 resonate, and the output terminal of the reception coil L2b, that is, the voltage of the load unit 7 is desired. The amplitude of the voltage, current, and power of the power supply unit 1 is controlled so that

  In the embodiment, the configuration is different from the conventional electromagnetic resonance method, and wireless power transmission is performed by the method described below.

3 is based on the leakage inductance L _e1 of the transmission unit 3b, the converted leakage inductance L ′ _e2 obtained by converting the leakage inductance L _e2 of the reception unit 5b to the transmission side, and the mutual inductance M seen from the transmission side. an equivalent circuit diagram of the receiving side when expressed by an equivalent circuit consisting, 4, to the mutual inductance M between the voltage V _M, the voltage drop _V'Le2 in terms leakage inductance _L'e2 of the reception side, the voltage drop _V'Lw2 in terms wiring inductance _L'w2 converted to the transmission side in the receiving side, and the voltage drop _V'Lr in terms inductance L'r converted to the sender of the inductance Lr of the load unit 7, the load A vector composition of the voltage drop V ′ _r at the resistance R ′ converted to the transmission side of the resistance R of the unit 7, the current I _M of the mutual inductance M, and the current I ′ _L converted to the transmission side to the load unit 7 Illustration A. _{Here, V'Le2, V'Lw2, V'} Lr is in phase, _V'r, these 90-degree phase are different. I _M is an exciting current flowing in the mutual inductance V _M , and I ′ _L is a load current flowing on the receiving side. In this specification, in each figure, the voltage, the symbol V _M of the _{current, V'Le2, V'Lw2, V'} Lr, I'L, vector symbols to be subjected to such I _M are omitted.

In this equivalent circuit diagram, the frequency f of the power source unit 1 is set for the capacitance C ₁ of the capacitive element C _{1 b} , the transmission-side combined inductance L ₁ , the reception-side transmission-side converted combined inductance L ′ ₂ , and the mutual inductance M, respectively. It sets so that following Formula (1) may be materialized. In this case, the transmission side combined inductance L ₁ , the receiving side transmission side converted combined inductance L ′ ₂ , and the mutual inductance M change with the coil interval. The frequency is controlled so that the resonance state is maintained even if there is such a change. Note that the conversion of the L ′ _e2 , L ′ _w2 , L′ r, etc. to the transmission side, and the mutual inductance M, etc. have been described in the section of the background art, and the description thereof will be omitted.

However, f is 20 kHz or more and about several MHz or less. L ₁ is the inductance Lg of the power supply unit 1 + the transmission side wiring inductance L _w1 + the leakage inductance L _e1 of the transmission coil L1b, and L ′ ₂ is the leakage converted to the transmission side of the leakage inductance L _e2 of the reception coil L2b. an inductance L'r converted to the sender of the inductance _L'e2 + wiring inductance in terms of sending and receiving wiring inductance L _{w2 L'w2} + load section 7 of the inductance Lr.

f = 1 / 2π [C ₁ [L ₁ + (L ′ ₂ · M) / (L ′ ₂ + M)]] ^1/2 (1)
When the formula (1) is satisfied, the inductance Lg of the power supply unit 1, the transmission-side wiring inductance L _w1, the inductance of the transmitting coil L1b, the capacitance C ₁ of the capacitor C1b, the inductance of the receiving coil L2b, converted wiring recipient inductance L _'w2, as converted inductance L'r the load section 7 resonates controls the frequency f of the power supply unit 1, the voltage of the load section 7 to a desired value, the voltage of the power supply unit 1, the current The amplitude of the power can be controlled.

As is evident in the vector diagram of FIG. 4, when considered in the equivalent circuit of the leakage inductance _L'e2 converted to the transmission side of the receiver coil L2b and leakage inductance L _e1 transmission coils L1b and the mutual inductance M , the voltage drop V _M of the mutual inductance M is the voltage vector, the voltage drop _V'Le2 + _V'Lw2 the conversion leakage inductance _L'e2 of the reception coil L2b and converted wiring inductance _L'w2 of the receiving side, the load section 7 The voltage drop V ′ _Lr due to the converted inductance L′ r and the voltage drop V′r due to the resistance R ′ converted to the transmission side in the resistance R of the load section 7, and the voltage drop V _M of the mutual inductance _M is , schematic, equals the voltage drop _V'L = _V'Lr + V'r the load section 7, passing a current _I'L from the mutual inductance M of the receiving portion 5c to the load section 7 It can transmit power to the load section 7.

Incidentally, further explaining conditions for transmitting the voltage across V _M of the mutual inductance M in the load section 7. Mutual inductance voltage across V _M is converted leakage inductance _L'e2 Te゛No voltage drop _V'Le2, voltage drop _V'LW2 in wiring inductance _L'w2 converted to the sender, converted inductance L'r the load section 7 is equal to the sum of the voltage drop V'r according converted resistor R'the sender due to a voltage drop _V'Lr, the resistance R of the load unit 7, these _{V M, V'Le2, V'LW2} , V'Lr, The following equation (2) is established between V′r.

_{V M = V'Le2 + V'LW2} + V'Lr + V'R ... (2)
Moreover, following Formula (3)-(6) is materialized.

V ' _Le2 = j · ω · L' _e2 · I ' _L (3)
_{V ′ LW2} = j · ω · L ′ _W2 · I ′ _L (4)
V ′ _Lr = j · ω · L ′ _r · I ′ _L (5)
V ′ _L = R ′ · I ′ _L (6)
From these, the following equation (7) is established.

V _M = [j · ω (L ′ _e2 + L ′ _W2 + L ′ _r ) + R ′] · I ′ _L (7)
From the equations (6) and (7), the following equation (8) is established.

V ′ _R = R ′ · I ′ _L = [R ′ / [j · ω (L ′ _e2 + L ′ _W2 + L ′ _r ) + R ′]] · V _M
... (8)
When absolute values are taken on both sides of the equation (8), the following equation (9) is established.

| V ′ _R | = R ′ / [ω ² (L ′ _e2 ² + L ′ _W2 ² + L ′ _r ² ) + R ′ ² ] ^1/2 · | V _M |
... (9)
| V ′ _R | / | V _M | = R ′ / [ω ² (L ′ _e2 ² + L ′ _W2 ²
+ L ′ ² _r ) + R ′ ² ] ^1/2 (10)
Therefore, if the value of formula (10) is more than about 0.7, most of the voltage across V _M of the mutual inductance M, can be transferred to the load unit 7.

  FIG. 5 is a diagram illustrating the resonance characteristics between the transmission side power and the reception side power with the frequency f on the horizontal axis and the power transmission efficiency (ratio of reception power / transmission power)% on the vertical axis. As shown in FIG. 5, the power transmission efficiency becomes the maximum efficiency when the frequency f is the resonance frequency fc. The resonance frequency fc is not particularly limited, but is preferably 20 kHz or more.

By the above, in the embodiment, the inductance Lg of the power supply unit 1, the transmission-side wiring inductance L _w1, the inductance of the transmitting coil L1b, capacitance C ₁ of the capacitor C1b, inductance L of the receive coil L2b, the receiving-side wiring inductance L _w2, the load unit When the resonance circuit including the inductance Lr 7 is controlled to resonate at the resonance frequency fc by controlling the frequency f of the power supply unit 1, the power of the power supply unit 1 can be transmitted to the load unit 7.

  As described above, in the present invention, the capacitor C1b is provided only on the transmission side, and power can be transmitted from the power supply unit 1 to the load unit 7 as a whole as a resonance circuit. A resonance circuit is configured with leakage inductance and capacitance on the receiving side and the receiving side, and it is no longer necessary to adjust the constants of the elements so that the resonance frequencies of the transmitting side and receiving side resonance circuits match. It became.

  In the present embodiment, the capacitor C1b is connected in series to the transmission coil L1b in the transmission unit 3b. However, as shown in FIG. 6, the reception of the reception unit 5c is performed without connecting the capacitor to the transmission coil L1c of the transmission unit 3c. A capacitor C2c may be connected in series to the coil L2c to form the resonance circuit, and power may be transmitted from the power supply unit 1 to the load unit 7 by this resonance circuit. However, in FIG. 6, the inductance of the power supply unit 1, the transmission side wiring inductance, the reception side wiring inductance, and the inductance of the load unit 7 are omitted.

  In this embodiment, a capacitor is connected in series to the transmission coil in the transmission unit. However, as shown in FIG. 7, an inductance L3 and a capacitor are connected to the power supply unit 1 without connecting a capacitor to the transmission coil L1d of the transmission unit 3d. A resonance circuit may be configured by connecting a series connection with C3 and connecting the transmission coil L1d to the capacitor C3. However, in FIG. 7, the inductance of the power supply unit 1, the transmission side wiring inductance, the reception side wiring inductance, and the inductance of the load unit 7 are omitted.

  In the present embodiment, the load unit is configured by a resistor, but is not limited thereto, and as illustrated in FIG. 8, as the load unit 7 a, a rectifier circuit 7 a 1 including diodes D 1 to D 4, A configuration including a capacitor C4, a resistor R, and the like connected to the DC output side of the rectifier circuit 7a1 may be employed. However, in FIG. 8, the inductance of the power supply unit 1, the transmission side wiring inductance, the reception side wiring inductance, and the inductance of the load unit 7 are omitted.

  Further, in the vicinity of the transmitting coil and the receiving coil, the transmitting coil generates and the magnetic flux generated by the transmitting coil does not decrease within the range where the magnetic flux generated by the transmitting coil does not decrease. A ferromagnetic material is disposed on the surface as necessary.

DESCRIPTION OF SYMBOLS 1 Power supply part 3b Transmission part 5b Reception part 7 Load part

  The present invention relates to a wireless power transmission apparatus that wirelessly transmits power.

  Wireless power transmission for transmitting power wirelessly has been performed for notebook PCs, pocket PCs, portable terminals, and other various devices and apparatuses.

  Such wireless power transmission is conventionally performed by an electromagnetic induction method.

  This electromagnetic induction system transmits power by electromagnetic coupling between a transmission coil and a reception coil (see Patent Document 1).

  An electromagnetic induction type wireless power transmission apparatus will be described with reference to FIG. 9. 1 is a power supply unit having a power supply Vg, 3 is a transmission unit having a transmission coil L1, and 5 is a reception coil L2 and a capacitive element in parallel therewith. A receiving unit 7 having C2 is a load unit by a resistor R.

  In the wireless power transmission device of FIG. 9, an electromagnetic field generated in the transmission coil L <b> 1 is guided to the reception coil L <b> 2 and power is transmitted to the load unit 7. Here, the capacitive element C2 of the receiving unit 5 is for obtaining a large induced electromotive force in the receiving coil L2.

  However, in the electromagnetic induction type wireless power transmission device shown in FIG. 9, the transmission coil L1 and the reception coil L2 need to be aligned, so that power transmission can be performed only at a considerably close distance.

  In 2006, MIT (Massachusetts Institute of Technology) announced a system for wirelessly transmitting power by electromagnetic resonance.

  The electromagnetic resonance system has a configuration in which capacitive elements are connected in series to both a transmission coil and a reception coil, and each includes an LC resonator.

In this electromagnetic resonance method, power transmission is performed using a near field (evanescent field) in which a magnetic field is dominant, and the pair of LC resonators are operated at a resonance frequency in the near field. Thus, the electromagnetic field energy generated by each LC resonator is resonated, whereby electric power is transmitted from the transmitting coil to the receiving coil (see Patent Document 2).

The wireless power transmission apparatus according to the electromagnetic resonance, with reference to FIG. 10, 1 is the power supply unit having a power source Vg, 3a transmission portion constituting the LC resonator in the transmit coil L1a the capacitor C1a, 5a is A receiving unit that configures an LC resonator by the capacitive element C2a and the receiving coil L2a , and 7 is a load unit formed by a resistor R.

In the transmission section 3a, and a transmission coil L1a and capacitance elements C1a and series resonance, thereby generating an electromagnetic field which vibrates in response to the resonant frequency near the transmitting coil L1a. In the receiving unit 5a, current flows through the receiving coil L2a upon receiving the electromagnetic field. At this time, in the receiving unit 5a, the receiving coil L2a and the capacitive element C2a constitute a series resonance circuit , and power is transmitted to the load unit 7 by these series resonance circuits . The resonance frequency of this electromagnetic resonance method is about 10 MHz, which is a higher frequency region than the electromagnetic induction method.

The wireless power transmission device shown in FIG. 10 can be represented by the equivalent circuit shown in FIG. Here, the inductance of the power supply unit 1, the wiring inductance on the transmission side and the reception side, and the inductance of the load unit 7 are ignored. In Figure 11, L _e1 is the leakage inductance in the transmission section 3a, L _e2 is the leakage inductance of the receiving unit 5a, _L'e2 is (as seen from the transmission side) obtained by converting the leakage inductance L _e2 to the transmitting side in terms inductance, Here, L ₁ represents the mutual inductance formed by the self-inductance L ₁₁ of the transmission coil L ₁ a and the self-inductance L ₂₂ of the reception coil L 2 a on the transmission side, and k · L ₁₁ when the coupling coefficient is k. be equivalent to. C2, the capacitance C _2, C ₂ 'is the capacitance obtained by converting the capacitance C ₂ of the capacitor C2a on the transmission side of the capacitor C2a, R is the resistance of the load unit 7, R'is a resistance R of the load section 7 to the transmitting side The converted resistance, R2 is a resistance on the reception side, and R2 ′ is a resistance converted from the resistance R2 on the reception side to the transmission side. These leakage inductances converted to the transmission side may be referred to as transmission-side conversion leakage inductances .

In wireless power transmission device represented by such equivalent circuit, the inductance L _e1 in the transmission section 3a, the resonant circuit composed of the capacitor C ₁ Metropolitan mutual inductance M and the capacitor C1a resonates the inductance _L'e2 in the receiving portion 5a The resonance circuit composed of the mutual inductance M and the transmission side equivalent capacitance C ₂ ′ of the capacitor C2a resonates, and the coupling coefficient k between the transmission coil L1a and the reception coil L2a ( the coupling coefficient between the transmission coil L1a and the reception coil L2a). The power transmission is performed when the coupling coefficient k is large and the resonance frequency is two resonance frequencies, and when the coupling coefficient k is small, the resonance frequency coincides with one resonance frequency or is close to coincidence .

  In such a wireless power transmission device using the electromagnetic resonance method, the power transmission efficiency is lower than that of the electromagnetic induction method, but there is an advantage that the power transmission distance can be extended.

Japanese Patent Laid-Open No. 10-145987 JP 2010-267917 A

However, in the conventional electromagnetic resonance type wireless power transmission device, both the transmission unit 3a and the reception unit 5a require the capacitive elements C1 and C2, but the positional relationship between the transmission unit 3a and the reception unit 5a changes. Then, the coupling coefficient k between the transmission coil L1a and the reception coil L2a changes, but since there are two resonance circuits, when the coupling coefficient k changes greatly, the coupling coefficient k changes slightly at two resonance frequencies. Resonates at one resonance frequency, and it is not easy to set capacitance in the capacitive elements C1 and C2 for electromagnetic resonance, and there is a problem that control of power transmission is complicated and difficult.

  The present invention has been made in view of the above, and by controlling the voltage, current, power, and frequency of the power supply even if the positional relationship between the transmission coil and the reception coil, which is a drawback of the electromagnetic induction system, changes. A new wireless power transmission that can cope with misalignment and eliminates the difficulty of wireless power transmission setting work, which is a drawback of the electromagnetic resonance system, and can extend the power transmission distance in the same way as the electromagnetic resonance system. A device is provided.

A wireless power transmission device according to the present invention includes a power supply unit having a function of controlling an amplitude and frequency of output voltage, output current, or output power, a transmission unit including a transmission coil connected to the power supply unit, and the transmission coil A receiving unit including a receiving coil arranged at an interval between the receiving unit and a load unit connected to the receiving unit, wherein the power of the power supply unit is transmitted to the load unit side through the two coils. A capacitor is connected to any one of the power supply unit, the transmission unit, and the reception unit to form a single resonance circuit, and the resonance circuit operates by controlling the frequency in the power supply unit. By transmitting the power, the power is transmitted.

The load unit is constituted by, for example, resistors, the value of the resistance as well as the R, and the resistance value R was converted to the sender resistor R', and the leakage inductance L _e2 of the reception coil _L'e2 As the leakage inductance converted to the transmission side, the value of [R ′ / [ω ² (L ′ _e2 ) ² + (R ′) ² ] ^1/2 is about 0.7 or more, that is, R ′ ≧ ω · L ′. _By setting it to about _e2, power can be transmitted with the voltage across the mutual inductance being equivalent to the voltage across the load.

  In this case, when considering an equivalent circuit in which the transmission coil and the reception coil are divided into leakage inductance and mutual inductance and the mutual inductance of the reception coil is converted into the mutual inductance of the transmission coil, the voltage drop at the mutual inductance in the voltage vector is This is a combination of the voltage drop between the leakage inductance of the receiving coil and the receiving side wiring inductance and the voltage drop at the load. The voltage drop of the mutual inductance is roughly equal to the load voltage drop, and the mutual inductance of the receiver. The electric power can be transmitted to the load unit by causing a current to flow through the load unit.

  The load section is not limited to a resistor, and includes a rectifier circuit, a capacitor connected to the DC output side of the rectifier circuit, a resistor, and the like, as well as other load circuits.

  The transmission unit is not limited to being configured with a transmission coil, and includes wiring inductance and the like.

  The receiving unit is not limited to a receiving coil, and includes a wiring inductance.

  Preferably, in addition to controlling the frequency in the power supply unit to cause the resonance circuit to resonate, the power is transmitted by controlling the amplitude of the output voltage, output current, or output power. Is preferred.

  Preferably, the resonance circuit includes a series connection body of a transmission coil of the transmission unit and a capacitor connected in series to the transmission coil.

  Preferably, the resonance circuit includes a series connection body of a reception coil of the reception unit and a capacitor connected in series to the reception coil.

  Preferably, the resonance circuit is configured by a serial connection body of an inductance and a capacitor of the power supply unit, and the capacitor is connected in parallel to the transmission coil.

  Preferably, the inductance that determines the resonance frequency of the resonance circuit includes a wiring inductance.

  Preferably, a ferromagnetic material is disposed in the vicinity of the transmission coil and the reception coil.

  In addition, although said power supply part, a transmission coil, a receiving coil, each capacitor | condenser, and each wiring inductance have resistance, it is not mentioned in this specification.

Preferably, the expressed by an equivalent circuit of the transmitter coil and the receiver coil and the leakage inductance and mutual inductance, and the inductance Lg of the power supply unit, and the transmitting-side wiring inductance L _w1, the combined inductance of the leakage inductance L _e1 transmission coils LΣ ₁ , the combined inductance LΣ ₂ of the receiving coil leakage inductance Le ₂ , the receiving side wiring inductance L _w2, and the load portion inductance L _r converted to the transmitting side is L′ Σ ₂ , from the transmitting side. Assuming that the mutual inductance between the transmission coil and the reception coil is L ₁ , the following expression (1) is satisfied with respect to the frequency f of the power supply unit.

f = 1 / 2π [C ₁ [ LΣ ₁ + ( L′ Σ ₂ · L ₁ ) / (( L′ Σ ₂ · L ₁ ) ]] ^1/2
The load unit is constituted by, for example, resistors, the value of the resistance as well as the R, and the resistance value R was converted to the sender resistor R', and the leakage inductance L _e2 of the reception coil _L'e2 As the leakage inductance converted to the transmission side, the value of [R ′ / [ω ² (L ′ _e2 ) ² + (R ′) ² ] ^1/2 is about 0.7 or more, that is, R ′ ≧ ω · L ′. _By setting it to about _e2, power can be transmitted with the voltage across the mutual inductance being equivalent to the voltage across the load.

  In the present invention, the capacitive element is connected in series to the transmission coil in the transmission unit, but the capacitive element is connected in series to the reception coil on the reception unit side without connecting the capacitive element to the transmission coil. A resonance circuit may be configured by a receiving coil and a capacitive element in series on the receiving coil, and power may be transmitted from the transmission unit to the reception unit by the resonance circuit.

  Further, a resonance circuit may be configured by connecting a series connection body of an inductance and a capacitor to the power supply unit and connecting a transmission coil to the capacitor.

  Furthermore, you may comprise a load part with the parallel circuit of a rectifier circuit, a capacitor | condenser, and resistance.

  In the present invention, the inductance of the power supply unit, the transmission side wiring inductance, the transmission coil leakage inductance, the mutual inductance of the transmission coil and the reception coil, the capacitance by the capacitive element, the leakage inductance of the reception coil, the reception side wiring inductance, and the load unit inductance The frequency of the power supply unit is controlled so as to resonate, and the voltage of the power supply unit or the amplitude of the current or power is controlled so that the output terminal of the receiving coil, that is, the voltage of the load unit becomes a desired value. is there.

  In this case, when considering an equivalent circuit in which the transmission coil and the reception coil are divided into leakage inductance and mutual inductance and the mutual inductance of the reception coil is converted into the mutual inductance of the transmission coil, the voltage drop at the mutual inductance in the voltage vector is This is a combination of the voltage drop between the leakage inductance of the receiving coil and the receiving side wiring inductance and the voltage drop at the load. The voltage drop of the mutual inductance is roughly equal to the load voltage drop, and the mutual inductance of the receiver. The electric power can be transmitted to the load unit by causing a current to flow through the load unit.

  As described above, in the present invention, the inductance of the power supply unit, the transmission side wiring inductance, the transmission coil leakage inductance, the transmission coil and the reception coil mutual inductance, the capacitance of the capacitive element, the reception coil leakage inductance, the reception side wiring inductance, the load By controlling the frequency of the power supply part so that the part inductance resonates, it is possible to transmit power to the load part, and by connecting a capacitive element to each of the transmission side and the reception side required for conventional electromagnetic resonance. It is no longer necessary to configure a resonant circuit, making it easy to set up power transmission.

FIG. 1 is a model diagram of a wireless power transmission device according to an embodiment of the present invention. FIG. 2 is a model diagram in the case of considering the power source inductance, the wiring inductance, and the load inductance in the apparatus of FIG. FIG. 3 is an equivalent circuit diagram viewed from the transmission side of FIG. FIG. 4 is a diagram showing vector synthesis of the voltage between the reception side leakage inductance and the reception side wiring inductance and the voltage across the load section with respect to the voltage between the mutual inductances. FIG. 5 is a diagram illustrating resonance characteristics between the transmission-side power and the reception-side power. FIG. 6 is a model diagram of a wireless power transmission device according to another embodiment of the present invention. FIG. 7 is a model diagram of a wireless power transmission apparatus according to still another embodiment of the present invention. FIG. 8 is a model diagram of a wireless power transmission apparatus according to still another embodiment of the present invention. FIG. 9 is a schematic diagram of an electromagnetic induction wireless power transmission device. FIG. 10 is a schematic diagram of an electromagnetic resonance wireless power transmission device. FIG. 11 is an equivalent circuit diagram seen from the transmission side of FIG.

  Hereinafter, a wireless power transmission device according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  Referring to FIG. 1, this apparatus includes a power supply unit 1 having a power supply Vg as a power transmission source, a transmission unit 3b including a capacitive element C1b and a transmission coil L1b, and a reception unit 5b having a reception coil L2b. And a load unit 7 as a power transmission destination. The power supply unit 1 has a function of controlling the amplitude and frequency of the output voltage or output voltage or output power.

  This wireless power transmission apparatus is schematically shown in FIG. The transmission unit 3b and the reception unit 5b are arranged at an interval. The power from the power supply unit 1 is transmitted from the transmission unit 3b, received by the reception unit 5b, and transmitted to the load unit 7.

  In the embodiment, the load unit 7 is indicated by a resistor R, but is not limited thereto. Although the transmission unit 3b has a single capacitor C1b, the transmission unit 3b is not limited to a single unit, and the form thereof may be connected in series to the transmission coil L1b. The transmission unit 3b is connected to the power supply unit 1 in series. Unlike the existing electromagnetic resonance type wireless power transmission apparatus, the receiving unit 5b does not have a capacitor connected in series to the receiving coil L2b.

FIG. 1 is a model diagram that does not consider the inductance of the power supply unit 1, its resistance, the wiring inductance on the transmission side, its resistance, the inductance of the load unit 7, and its resistance. On the other hand, FIG. 2 is a model diagram in consideration of the inductance Lg of the power supply unit 1, the inductance L _{w1 of} the transmission side wiring, the inductance L _w2 of the reception side wiring, and the inductance Lr of the load unit 7. In this figure, the resistance of the power supply unit 1, the resistance of the wiring inductance on the transmission side, and the resistance of the inductance of the load unit 7 are not considered.

In the wireless power transmission device of the embodiment, the capacitance C _{1 of the} capacitor C1b, the inductance Lg of the power supply unit 1, the transmission-side wiring inductance L _w1 , the leakage inductance of the transmission coil L1b, the mutual inductance of the transmission coil L1b and the reception coil L2b, the reception coil The frequency of the power supply unit 1 is controlled so that the leakage inductance of L2b, the reception side wiring inductance _Lw2 , and the inductance Lr of the load unit 7 resonate, and the output terminal of the reception coil L2b, that is, the voltage of the load unit 7 is desired. The amplitude of the voltage, current, and power of the power supply unit 1 is controlled so that

  In the embodiment, the configuration is different from the conventional electromagnetic resonance method, and wireless power transmission is performed by the method described below.

FIG. 3 shows the leakage inductance L _e1 of the transmission unit 3b, the converted leakage inductance L ′ _e2 obtained by converting the leakage inductance L _e2 of the reception unit 5b to the transmission side, and the mutual inductance L ₁ seen from the transmission side. an equivalent circuit diagram of the receiving side when expressed by an equivalent circuit consisting of, 4, to the mutual inductance L ₁ between the voltage V _L1, the voltage drop in the conversion leakage inductance _L'e2 of the reception side _V'Le2 When a voltage drop _V'Lw2 in terms wiring inductance _L'w2 converted to the transmission side in the receiving side, and the voltage drop _V'Lr in terms inductance L'r converted to the sender of the inductance Lr of the load section 7 The voltage drop V ′ _r at the resistance R ′ converted to the transmission side of the resistance R of the load unit 7, the current I _M of the mutual inductance M, and the current I ′ _L converted to the transmission side to the load unit 7. Shows composition It is a diagram. _{Here, V'Le2, V'Lw2, V'} Lr is in phase, _V'r, these 90-degree phase are different. I _M is an exciting current flowing in the mutual inductance L ₁ , and I ′ _L is a load current flowing on the receiving side. In this specification, in each figure, the voltage, the symbol V _L1 of the _{current, V'Le2, V'Lw2, V'} Lr, I'L, vector symbols to be subjected to such I _M are omitted.

In this equivalent circuit diagram, the frequency f of the power supply unit 1 is set for the capacitance C ₁ of the capacitive element C _{1 b} , the transmission-side combined inductance L ₁ , the reception-side transmission-side converted combined inductance L ′ ₂ , and the mutual inductance L _1. Then, the following equation (1) is set. In this case, the combined inductance LΣ ₁ on the transmitting side, the converted equivalent inductance L′ Σ ₂ on the receiving side, and the mutual inductance L ₁ vary with the coil interval. The frequency is controlled so that the resonance state is maintained even if there is such a change. Note that the conversion of the L ′ _e2 , L ′ _w2 , L′ r, etc. to the transmission side, and the mutual inductance L ₁ , etc. have been described in the section of the background art, and will not be described.

However, f is 20 kHz or more and about several MHz or less. Further, Erushiguma _1, the inductance of the power supply unit 1 Lg + sender wiring inductance L _w1 + a leakage inductance L _e1 transmission coils L1b, L'Σ ₂ was converted to the sender of the leakage inductance L _e2 of the reception coil L2b an inductance L'r converted to the transmission side of the leakage inductance _L'e2 + wiring inductance in terms of sending and receiving wiring inductance L _{w2 L'w2} + load section 7 of the inductance Lr.

f = 1 / 2π [C ₁ [ LΣ ₁ + (L´Σ ₂ ・ L ₁ ) / ((L´Σ ₂ ・ L ₁ ) ]] ^1/2 … (1)
When the formula (1) is satisfied, the inductance Lg of the power supply unit 1, the transmission-side wiring inductance L _w1, the inductance of the transmitting coil L1b, the capacitance C ₁ of the capacitor C1b, the inductance of the receiving coil L2b, converted wiring recipient inductance L _'w2, as converted inductance L'r the load section 7 resonates controls the frequency f of the power supply unit 1, the voltage of the load section 7 to a desired value, the voltage of the power supply unit 1, the current The amplitude of the power can be controlled.

As it is evident in the vector diagram of FIG. 4, considered in the equivalent circuit of the leakage inductance _L'e2 and the mutual inductance L ₁ of the leakage inductance L _e1 converted to the transmission side of the receiver coil L2b transmission coils L1b If the voltage drop V _L1 of the mutual inductance L ₁ is the voltage vector, the voltage drop _V'Le2 + _V'Lw2 the conversion leakage inductance _L'e2 of the reception coil L2b and converted wiring inductance _L'w2 of the receiving side, the load The voltage drop V ′ _Lr due to the converted inductance L′ r of the unit 7 and the voltage drop V′r due to the resistor R ′ converted to the transmission side in the resistance R of the load unit 7, and the voltage drop V of the mutual inductance M _M is approximately equal to the voltage drop V ′ _L = V ′ _Lr + V′r of the load unit 7, and the current I ′ _L is caused to flow from the mutual inductance L ₁ of the receiving unit 5 c to the load unit 7. Thus, power can be transmitted to the load unit 7.

The conditions for transmitting the voltage V _L1 across the mutual inductance L ₁ to the load unit 7 will be further described. Mutual inductance between both ends voltages V _L1 is converted leakage inductance _L'e2 Te゛No voltage drop _V'Le2, voltage drop _V'LW2 in wiring inductance _L'w2 converted to the sender, converted inductance L'r the load section 7 is equal to the sum of the voltage drop V'r according converted resistor R'the sender due to a voltage drop _V'Lr, the resistance R of the load unit 7, these _{V L1, V'Le2, V'LW2} , V'Lr, The following equation (2) is established between V′r.

_{V L1 = V'Le2 + V'LW2} + V'Lr + V'R ... (2)
Moreover, following Formula (3)-(6) is materialized.

V ' _Le2 = j · ω · L' _e2 · I ' _L (3)
_{V ′ LW2} = j · ω · L ′ _W2 · I ′ _L (4)
V ′ _Lr = j · ω · L ′ _r · I ′ _L (5)
V ′ _L = R ′ · I ′ _L (6)
From these, the following equation (7) is established.

V _L1 = [j · ω (L ′ _e2 + L ′ _W2 + L ′ _r ) + R ′] · I ′ _L (7)
From the equations (6) and (7), the following equation (8) is established.

V ′ _R = R ′ · I ′ _L = [R ′ / [j · ω (L ′ _e2 + L ′ _W2 + L ′ _r ) + R ′]] · V _L1 (8)
When absolute values are taken on both sides of the equation (8), the following equation (9) is established.

| V ′ _R | = R ′ / [ω ² (L ′ _e2 ² + L ′ _W2 ² + L ′ _r ² ) + R ′ ² ] ^1/2 · | V _L1 | (9)
| V ′ _R | / | V _L1 | = R ′ / [ω ² (L ′ _e2 ² + L ′ _W2 ²
+ L ′ ² _r ) + R ′ ² ] ^1/2 (10)
Therefore, if the value of Expression (10) is about 0.7 or more, most of the voltage V _L1 across the mutual inductance L ₁ can be transmitted to the load unit 7.

  FIG. 5 is a diagram illustrating the resonance characteristics between the transmission side power and the reception side power with the frequency f on the horizontal axis and the power transmission efficiency (ratio of reception power / transmission power)% on the vertical axis. As shown in FIG. 5, the power transmission efficiency becomes the maximum efficiency when the frequency f is the resonance frequency fc. The resonance frequency fc is not particularly limited, but is preferably 20 kHz or more.

By the above, in the embodiment, the inductance Lg of the power supply unit 1, the transmission-side wiring inductance L _w1, the inductance of the transmitting coil L1b, capacitance C ₁ of the capacitor C1b, inductance L of the receive coil L2b, the receiving-side wiring inductance L _w2, the load unit When the resonance circuit including the inductance Lr 7 is controlled to resonate at the resonance frequency fc by controlling the frequency f of the power supply unit 1, the power of the power supply unit 1 can be transmitted to the load unit 7.

  As described above, in the present invention, the capacitor C1b is provided only on the transmission side, and power can be transmitted from the power supply unit 1 to the load unit 7 as a whole as a resonance circuit. A resonance circuit is configured with leakage inductance and capacitance on the receiving side and the receiving side, and it is no longer necessary to adjust the constants of the elements so that the resonance frequencies of the transmitting side and receiving side resonance circuits match. It became.

  In the present embodiment, the capacitor C1b is connected in series to the transmission coil L1b in the transmission unit 3b. However, as shown in FIG. 6, the reception of the reception unit 5c is performed without connecting the capacitor to the transmission coil L1c of the transmission unit 3c. A capacitor C2c may be connected in series to the coil L2c to form the resonance circuit, and power may be transmitted from the power supply unit 1 to the load unit 7 by this resonance circuit. However, in FIG. 6, the inductance of the power supply unit 1, the transmission side wiring inductance, the reception side wiring inductance, and the inductance of the load unit 7 are omitted.

  In this embodiment, a capacitor is connected in series to the transmission coil in the transmission unit. However, as shown in FIG. 7, an inductance L3 and a capacitor are connected to the power supply unit 1 without connecting a capacitor to the transmission coil L1d of the transmission unit 3d. A resonance circuit may be configured by connecting a series connection with C3 and connecting the transmission coil L1d to the capacitor C3. However, in FIG. 7, the inductance of the power supply unit 1, the transmission side wiring inductance, the reception side wiring inductance, and the inductance of the load unit 7 are omitted.

  In the present embodiment, the load unit is configured by a resistor, but is not limited thereto, and as illustrated in FIG. 8, as the load unit 7 a, a rectifier circuit 7 a 1 including diodes D 1 to D 4, A configuration including a capacitor C4, a resistor R, and the like connected to the DC output side of the rectifier circuit 7a1 may be employed. However, in FIG. 8, the inductance of the power supply unit 1, the transmission side wiring inductance, the reception side wiring inductance, and the inductance of the load unit 7 are omitted.

  Further, in the vicinity of the transmitting coil and the receiving coil, the transmitting coil generates and the magnetic flux generated by the transmitting coil does not decrease within the range where the magnetic flux generated by the transmitting coil does not decrease. A ferromagnetic material is disposed on the surface as necessary.

DESCRIPTION OF SYMBOLS 1 Power supply part 3b Transmission part 5b Reception part 7 Load part

A wireless power transmission device according to the present invention includes a power supply unit having a function of controlling an amplitude and frequency of output voltage, output current, or output power, a transmission unit including a transmission coil connected to the power supply unit, and the transmission coil A receiving unit including a receiving coil arranged at an interval between the receiving unit and a load unit connected to the receiving unit, wherein the power of the power supply unit is transmitted to the load unit side through the two coils. A capacitor is connected to any one of the power supply unit, the transmission unit, and the reception unit to form a single resonance circuit, and the resonance circuit operates by controlling the frequency in the power supply unit. Thus, while transmitting the electric power , the load portion includes a resistor, the resistance value is R, the resistance value R is converted to the resistance R ′, and L ′ _e2 The receiving The value of [R ′ / [ω ² (L ′ _e2 ) ² + (R ′) ² ] ^1/2 is about 0.7 or more as the leakage inductance converted from the coil leakage inductance L _e2 to the transmitting side , that is, By setting R ′ ≧ ω · L ′ _e2 , electric power is transmitted by setting the voltage across the mutual inductance of both the coils to the same level as the voltage across the load portion .

f = 1 / 2π [C ₁ [LΣ ₁ + (L′ Σ ₂ · L ₁ ) / ((L′ Σ ₂ + L ₁ )]] ^1/2 (1)
The load unit is constituted by, for example, resistors, the value of the resistance as well as the R, and the resistance value R was converted to the sender resistor R', and the leakage inductance L _e2 of the reception coil _L'e2 As the leakage inductance converted to the transmission side, the value of [R ′ / [ω ² (L ′ _e2 ) ² + (R ′) ² ] ^1/2 is about 0.7 or more, that is, R ′ ≧ ω · L ′. _By setting it to _e2 , electric power can be transmitted by setting the voltage across the mutual inductance to the same level as the voltage across the load.

In the present invention, the inductance of the power supply unit, transmitting-side wiring inductance, leakage inductance of the transmitting coil, the mutual inductance of the transmit coil receiving coil, the capacitance of the capacitive element, the receiving coil leakage inductance, the receiving-side wiring inductance, the load unit inductance Control the frequency of the power supply unit so that it operates at a determined frequency, and also control the amplitude of the voltage, current, or power of the power supply unit so that the output terminal of the receiving coil, that is, the voltage of the load unit becomes a desired value To do.

In this equivalent circuit diagram, the frequency f of the power supply unit 1 is set for the capacitance C ₁ of the capacitive element C _{1 b} , the transmission-side combined inductance L ₁ , the reception-side transmission-side converted combined inductance L ′ ₂ , and the mutual inductance L _1. Then, the following equation (1) is set. In this case, the transmission-side combined inductance LΣ ₁ , the reception-side transmission-side converted combined inductance L′ Σ ₂ , and the mutual inductance L ₁ vary with the coil interval. The frequency is controlled so that the resonance state is maintained even if there is such a change. Note that the conversion of the L ′ _e2 , L ′ _w2 , L′ r, etc. to the transmission side, and the mutual inductance L ₁ , etc. have been described in the section of the background art, and will not be described.

f = 1 / 2π [C ₁ [LΣ ₁ + (L´Σ ₂・ L ₁ ) / ((L´Σ ₂ + L ₁ )]] ^1/2 … (1)
As the above formula (1) is satisfied, i.e., the inductance Lg, sender wiring inductance L _w1 of the power supply unit 1, the transmission coil L1b inductance, the capacitance C ₁ of the capacitor C1b, the receiving coil L2b inductance, the recipient The frequency f of the power supply unit 1 is controlled so as to operate at a frequency determined by the converted wiring inductance L ′ _w2 and the converted inductance L′ r of the load unit 7, and the voltage of the load unit 7 is set to a desired value. The amplitude of the voltage, current, and power of the power supply unit 1 can be controlled.

By the above, in the embodiment, the inductance Lg of the power supply unit 1, the transmission-side wiring inductance L _w1, the inductance of the transmitting coil L1b, capacitance C ₁ of the capacitor C1b, inductance L of the receive coil L2b, the receiving-side wiring inductance L _w2, the load unit 7 of the inductance Lr, against the resonant circuit consisting of a resistor R, by controlling the frequency f of the power supply unit 1 is operated at a frequency determined by the formula (1), transmits the power of the power supply unit 1 to the load section 7 be able to.

A wireless power transmission device according to the present invention includes a power supply unit having a function of controlling an amplitude and frequency of output voltage, output current, or output power, a transmission unit including a transmission coil connected to the power supply unit, and the transmission coil A receiving unit including a receiving coil arranged at an interval between the receiving unit and a load unit connected to the receiving unit, wherein the power of the power supply unit is transmitted to the load unit side through the two coils. In addition, a capacitor is connected to the transmission unit to form a single resonance circuit, and the resonance circuit is operated by controlling the frequency in the power supply unit, thereby transmitting the power, It includes a resistor to the load unit, the value of the resistance as well as the R, and converted to a resistor R'the resistance value R on the transmission side and the transmission side leakage inductance L _e2 of the reception coil _L'e2 In As the converted leakage inductance, the value of [R ′ / [ω ² (L ′ _e2 ) ² + (R ′) ² ] ^1/2 is about 0.7 or more, that is, R ′ ≧ ω · L ′ _e2 . Thus, the power is transmitted with the voltage across the mutual inductance in both the coils equal to the voltage across the load.

FIG. 3 is equivalent to FIG. 2 and consists of a leakage inductance Le1 of the transmission unit 3b, a converted leakage inductance L'e2 obtained by converting the leakage inductance Le2 of the reception unit 5b to the transmission side, and a mutual inductance L1 viewed from the transmission side. FIG. 4 is an equivalent circuit diagram on the receiving side in the case of a circuit. FIG. 4 shows a voltage drop V′Le2 at the conversion leakage inductance L′ e2 on the receiving side and a voltage drop V′Le2 on the receiving side with respect to the voltage VL1 between the mutual inductances L1. The voltage drop V′Lw2 at the converted wiring inductance L′ w2 converted to the transmission side, the voltage drop V′Lr at the conversion inductance L′ r converted to the transmission side of the inductance Lr of the load section 7, and the load section 7 voltage drop V'r in converted to the transmission side of the resistor R resistance R', FIG der showing the current IM of the mutual inductance L1, the vector synthesis of the current I'L converted to the transmission side to the load section 7 . Here, V′Le2, V′Lw2, and V′Lr are in phase, and V′r is 90 degrees out of phase with these. IM is an exciting current flowing in the mutual inductance L1, and I'L is a load current flowing on the receiving side. In the present specification, the vector symbols attached to the voltage and current symbols VL1, V'Le2, V'Lw2, V'Lr, I'L, IM, etc. are omitted in each drawing.

As apparent from the vector diagram of FIG. 4, when considering an equivalent circuit of the leakage inductance Le1 of the transmission coil L1b, the leakage inductance L'e2 converted to the transmission side of the reception coil L2b, and the mutual inductance L1, In the voltage vector, the voltage drop VL1 at the mutual inductance L1 is the voltage drop V'Le2 + V'Lw2 between the conversion leakage inductance L'e2 of the reception coil L2b and the conversion wiring inductance L'w2 on the reception side, and the conversion inductance of the load section 7. The voltage drop V′Lr due to L ′ r and the voltage drop V′r due to the resistance R ′ converted to the transmission side in the resistance R of the load unit 7, and the voltage drop VL1 of the mutual inductance L1 is roughly the load It is equal to the voltage drop V'L = V'Lr + V'r parts 7, a current is passed I'L from mutual inductance L1 of the receiver 5c to the load section 7 It is possible to transfer power to the load section 7.

Further, in the present embodiment, the load section is configured by a resistor, but is not limited to this, and as shown in FIG. 8, a rectifier circuit 7a1 including diodes D1 to D4 is used as the load section 7a. A configuration including a capacitor C4, a resistor R, and the like connected to the DC output side of the rectifier circuit 7a1 may be employed. However, in FIG. 8, the inductance of the power supply unit 1, the transmission side wiring inductance, the reception side wiring inductance, and the inductance of the load unit 7 are omitted.

Claims (8)

A power supply unit having a function of controlling the amplitude and frequency of output voltage or output current or output power, a transmission unit including a transmission coil connected to the power supply unit, and reception arranged at intervals in the transmission coil A device comprising a receiving unit including a coil, and a load unit connected to the receiving unit, wherein the power of the power supply unit is transmitted to the load unit side via both coils,
A resonance circuit is configured by connecting a capacitor to any one of the power supply unit, the transmission unit, and the reception unit, and the resonance circuit is resonated by the frequency control in the power supply unit, thereby transmitting the power. A wireless power transmission device characterized in that   The power transmission is performed by controlling an amplitude of an output voltage, an output current, or an output power in addition to controlling the frequency in the power supply unit to cause the resonance circuit to resonate. Equipment.   The apparatus according to claim 1, wherein the resonance circuit includes a series connection body of a transmission coil of the transmission unit and a capacitor connected in series to the transmission coil.   The apparatus according to claim 1, wherein the resonance circuit includes a serial connection body of a reception coil of the reception unit and a capacitor connected in series to the reception coil.   The apparatus according to claim 1, wherein the resonance circuit is configured by a serial connection body of an inductance and a capacitor of the power supply unit, and the capacitor is connected in parallel to the transmission coil.   The apparatus according to claim 1, wherein a wiring inductance is included in an inductance that determines a resonance frequency of the resonance circuit. The transmission coil and the reception coil are represented by an equivalent circuit of a leakage inductance and a mutual inductance, and a combined inductance of the power supply unit inductance Lg, the transmission-side wiring inductance L _w1, and the transmission coil leakage inductance L _e1 is L _1. , a leakage inductance L _e2 receiving coil, a receiving-side wiring inductance L _w2, the combined inductance L _{2 L'2} the combined inductance converted to the transmission side of the inductance L _r of the load unit, a transmit coil viewed from the transmission side The apparatus according to claim 1, wherein the mutual inductance with the receiving coil is M and the following expression (1) is satisfied with respect to the frequency f of the power supply unit.
f = 1 / 2π [C ₁ [L ₁ + (L ′ ₂ · M) / (L ′ ₂ + M)]] ^1/2 (1)   The apparatus according to claim 1, wherein a ferromagnetic material is disposed in the vicinity of the transmission coil and the reception coil.

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