JP6565464B2 - Coil structure, power transmitter, power receiver, and wireless power transmission system - Google Patents

Description

  The embodiments referred to in this application relate to coil structures, power transmitters, power receivers, and wireless power transfer systems.

  2. Description of the Related Art In recent years, wireless power transfer (Wireless Power Transfer) technology that transmits power wirelessly has attracted attention in order to supply power and charge. For example, wireless power transmission systems that wirelessly transmit power to various electronic devices such as mobile terminals and notebook computers, home appliances, and power infrastructure devices such as automobiles have been researched and developed.

  Conventionally, as a wireless power transmission technique, a technique using electromagnetic induction or a technique using radio waves is generally known, but in recent years, wireless power transmission has been performed while separating the distance between the power transmitter and the power receiver to some extent. Wireless power transmission using possible magnetic field resonance (magnetic field resonance) is promising.

  By the way, various proposals have been made for wireless power transmission technology.

JP 2011-050127 A JP 2012-151111 A JP 2014-014258 A International Publication No. 2011/114527

  As described above, for example, wireless power transmission using magnetic field resonance has attracted attention. To improve power feeding from a power transmitter (power transmission resonance coil) to a power receiver (power reception resonance coil), kQ is increased. Is preferred.

  Here, k (k value) indicates the degree of electromagnetic field coupling, the larger the value, the greater the degree of coupling, and Q (Q value), the degree of electromagnetic field loss, The larger the value, the smaller the degree of loss.

  As a method for increasing kQ, for example, the use of a magnetic core is conceivable, but there are restrictions on the size and weight of many power supply target devices. For example, in the plane type (coil facing type) where the power transmission coil (power transmission resonance coil) and the power reception coil (power reception resonance coil) face each other, the effect of the relative permeability α is reduced by the demagnetizing field in the thin plate-shaped core. Therefore, there is a possibility that a great effect cannot be obtained.

  Further, in order to increase k in the coil-facing type, for example, it is conceivable to increase the coil area. However, the increase in the coil area is limited by an allowable size, and causes an increase in radiation loss. It will also be a thing.

  Further, it is conceivable to decrease the coil resistance R in order to increase the Q. However, for example, a problem of cost due to the use of an expensive coil material or a problem of size and weight when the coil is thickened. Also occurs.

  According to one embodiment, a first magnetic body portion, a second magnetic body portion facing the first magnetic body portion, and a first magnetic body portion provided between the first magnetic body portion and the second magnetic body portion. A coil structure having a three magnetic body part and a coil wound around the third magnetic body part is provided.

The area of the third magnetic body portion in the coil is smaller than the areas of the first magnetic body portion and the second magnetic body portion. The ratio between the first magnetic flux that passes through the third magnetic body portion in the coil and the larger second magnetic flux among the magnetic fluxes that pass through the first magnetic body portion and the second magnetic body portion is within the coil. This is a value larger than the fourth root of the ratio of the first projected area of the third magnetic body portion to the larger second projected area of the first magnetic body portion and the second magnetic body portion. .

  The disclosed coil structure, power transmitter, power receiver, and wireless power transmission system have an effect that kQ can be increased.

FIG. 1 is a diagram schematically illustrating an example of a power transmission system. FIG. 2 is a diagram schematically illustrating an example of a two-dimensional and three-dimensional wireless power transmission system. FIG. 3 is a diagram for explaining power supply efficiency (kQ) in the wireless power transmission system. FIG. 4 is a diagram schematically illustrating the coil structure according to the present embodiment. FIG. 5 is a diagram for explaining convergence of the interlinkage magnetic flux by the coil structure shown in FIG. FIG. 6 is a diagram for explaining a reduction in coil resistance by the coil structure of the present embodiment. FIG. 7 is a diagram for explaining the effect of this embodiment. FIG. 8 is a block diagram schematically illustrating an example of a wireless power transmission system. FIG. 9 is a diagram for explaining a modification of the transmission coil in the wireless power transmission system of FIG. 8. FIG. 10 is a diagram for explaining a first example of conditions in the coil structure according to the present embodiment. FIG. 11 is a diagram for explaining a second example of conditions in the coil structure according to the present embodiment. FIG. 12 is a diagram for explaining a third example of conditions in the coil structure according to the present embodiment. FIG. 13 is a diagram for explaining a fourth example of conditions in the coil structure according to the present embodiment. FIG. 14 is a diagram for explaining an example of the third magnetic body portion in the coil structure according to the present embodiment. FIG. 15 is a diagram for explaining an example of the first magnetic body portion and the second magnetic body portion in the coil structure according to the present embodiment. FIG. 16 is a diagram (part 1) illustrating an example of simulation by the coil structure according to the present embodiment. FIG. 17 is a diagram (part 2) illustrating an example of simulation by the coil structure according to the present embodiment.

  First, before describing embodiments of a coil structure, a power transmitter, a power receiver, and a wireless power transmission system in detail, an example of a power transmission system will be described with reference to FIGS. 1 and 2. Here, FIGS. 1 and 2 show and explain smartphones and notebook computers whose received power (required power) is several watts (W) to several tens of watts, but this embodiment described later in detail is limited to these. In addition, the present invention can be applied to household electric appliances, electric vehicles, and the like that handle higher power.

  In addition, the coil structure of the present embodiment is, for example, for either one of the resonance coil of the power transmitter and the resonance coil of the power receiver in the wireless power transmission system using magnetic field resonance, or both resonance coils. Can be applied.

  FIG. 1 is a diagram schematically showing an example of a power transmission system, FIG. 1 (a) shows an example of a wired power transmission (wire connection power supply) system, and FIG. 1 (b) shows a wireless power transmission ( An example of a wireless power supply system is shown. In FIG. 1A and FIG. 1B, reference numerals 2A1 to 2C1 denote power receivers, respectively.

  Here, the power receiver 2A1 represents, for example, a tablet with a received power of 10W, the power receiver 2B1 represents, for example, a notebook computer with a received power of 50W, and the power receiver 2C1 has, for example, a received power of 2.5W. Indicates a smartphone. The received power corresponds to, for example, power for charging a rechargeable battery (secondary battery) in each of the power receivers 2A1 to 2C1.

  As shown in FIG. 1A, when charging the secondary battery of the tablet 2A1 or the smartphone 2C1, normally, for example, a personal computer USB (Universal Serial Bus) terminal (or a dedicated power source or the like) 3A Are connected via power cables 4A and 4C. Further, when charging the secondary battery of the notebook personal computer 2B1, for example, it is connected to a dedicated power supply device (AC-DC Converter) 3B via the power cable 4B.

  That is, as shown in FIG. 1 (a), even if the portable power receivers 2A1 to 2C1 are generally connected by wire connection from the USB terminal 3A or the power supply device 3B using the power cables 4A to 4C. Power supply (wired power transmission) is performed.

  By the way, in recent years, wireless power feeding (wireless power transmission) has been put into practical use, for example, with a shaver, an electric toothbrush, or the like, due to progress in non-contact power feeding technology represented by electromagnetic induction. Therefore, as shown in FIG. 1B, for example, it is considered to transmit wireless power from the power transmitter 1A1 to the tablet 2A1, the notebook computer 2B1, and the smartphone 2C1.

  FIG. 2 is a diagram schematically illustrating an example of a two-dimensional and three-dimensional wireless power transmission system. Here, FIG. 2 (a) shows an example of a two-dimensional wireless power transmission (two-dimensional wireless power feeding) system. For example, like the above-described shaver and electric toothbrush, the wireless power transmission is performed by electromagnetic induction. Show. FIG. 2B schematically shows an example of a three-dimensional wireless power transmission (three-dimensional wireless power feeding) system, for example, showing how wireless power transmission is performed using magnetic field resonance.

  As shown in FIG. 2 (a), when wireless power transmission is performed using electromagnetic induction, since the power transmission distance is short even with non-contact power feeding, the power receiver 1A2 is almost in contact with the power receiver. Only electric appliances can supply power.

  In other words, even if power can be supplied to the power receiver (notebook computer) 2B2 placed on the power transmitter (power reception table) 1A2, power can be supplied to the notebook computer 2B3 that is remote from the power reception table 1A2. Have difficulty. As described above, the wireless power transmission system shown in FIG. 2A is a two-dimensional wireless power feeding system that allows free placement on the power receiving table 1A2.

  As shown in FIG. 2 (b), when wireless power transmission is performed using magnetic field resonance, a plurality of receivers existing within a predetermined range from the power transmitter 1A2 (inside the broken line in FIG. 2 (b)). It is possible to supply power to the electric appliance.

  That is, wireless power can be transmitted from the power transmitter 1A3 to the tablets 2A2 and 2A3, the notebook computers 2B2 and 2B3, and the smartphone 2C2 within a predetermined range. In FIG. 2 (b), only one power transmitter 1A3 is depicted, but a plurality of power transmitters are used for a plurality of power receivers at various angles and positions using magnetic field resonance or electric field resonance. Wireless power transmission is performed.

  In this way, the wireless power transmission system shown in FIG. 2 (b) is, for example, a third order that can obtain higher power transmission efficiency in a distant space than that using electromagnetic induction by using magnetic field resonance. It is an original wireless power supply system.

  In the above, the wireless power transmission system of the present embodiment uses magnetic field resonance with respect to a plurality of power receivers (power receiving resonance coils) at various angles and positions by, for example, a plurality of power transmitters (power transmission resonance coils). Thus, the present invention is not limited to a system that performs wireless power transmission. That is, the present embodiment can be applied to, for example, a system in which one power transmitter is brought close to one power receiver and power is wirelessly transmitted using magnetic field resonance.

  FIG. 3 is a diagram for explaining the power feeding efficiency (power transmission efficiency: kQ) in the wireless power transmission system, where the vertical axis represents the efficiency (ideal efficiency), and the horizontal axis represents kQ (product of k and Q: kQ value). Here, k (k value) indicates the degree of electromagnetic field coupling, and the larger the value, the greater the degree of coupling. Q (Q value) indicates the degree of electromagnetic field loss, and the larger the value, the smaller the loss. The efficiency is determined by kQ, but not efficiency = kQ. Regarding the description of the efficiency kQ and the like in this specification, it should be understood that the efficiency is determined by kQ.

KQ is expressed by the following equation (1). Here, Q ₁ indicates the Q value of the power transmitter, and Q ₂ indicates the Q value of the power receiver.
kQ = k × (Q ₁ Q ₂ ) ^1/2 …… (1)

K is expressed by the following equation (2). Here, M ₁₂ represents the mutual inductance between the power transmitter and the power receiver, L ₁ represents the self-inductance of the power transmitter, and L ₂ represents the self-inductance of the power receiver.
k = M ₁₂ / (L ₁ L ₂ ) ^1/2 (2)

Further, Q ₁ and Q ₂ are expressed by the following equation (3). Here, ω represents the angular frequency, R ₁ represents the resonance coil resistance (loss) of the power transmitter, and R ₂ represents the resonance coil resistance of the power receiver.
Q ₁ = ωL ₁ / R ₁ , Q ₂ = ωL ₂ / R ₂ (3)

  As shown in FIG. 3, for example, in a wireless power transmission of power transmission: power reception = 1: 1, a theoretical relationship is established between efficiency and kQ, and in order to realize high power transmission efficiency, It can be seen that it is preferable to increase kQ. As a method for increasing the kQ, for example, the use of a magnetic core is conceivable, but there are restrictions on the size and weight of many power supply target devices.

  For example, in the plane type (coil facing type) where the power transmission coil (power transmission resonance coil) and the power reception coil (power reception resonance coil) face each other, the effect of the relative permeability α is reduced by the demagnetizing field in the thin plate-shaped core. Therefore, there is a possibility that a great effect cannot be obtained.

  In order to increase k in the coil-facing type, for example, it is conceivable to increase the coil area. However, the increase in the coil area is limited by the allowable size and causes an increase in radiation loss. Also become.

  In order to increase Q (= ωL / R), for example, it is conceivable to increase the angular frequency (frequency) ω, but the increase in frequency is limited by the standard or the power supply band. Further, it is conceivable to increase the self-inductance (L). In this case, when the number of turns N of the coil is increased, there are problems of limitation due to size and proximity effect, and when a magnetic core (magnetic material) is used, there are problems of limitation due to size and limitation due to core loss.

  Further, it is conceivable to decrease the coil resistance R in order to increase the Q. However, for example, a problem of cost due to the use of an expensive coil material or a problem of size and weight when the coil is thickened. Also occurs.

  As described above, when the kQ is increased in the coil design, there is a limit mainly due to the size limitation, and it is actually quite difficult to reduce the resistance of the coil (for example, material development exceeding pure copper).

  Hereinafter, embodiments of a coil structure, a power transmitter, a power receiver, and a wireless power transmission system will be described in detail with reference to the accompanying drawings. FIG. 4 is a diagram schematically illustrating the coil structure according to the present embodiment, and FIG. 5 is a diagram for explaining convergence of the interlinkage magnetic flux by the coil structure illustrated in FIG. 4. In FIG. 4, reference numeral 51 denotes a first magnetic body portion, 52 denotes a second magnetic body portion, 53 denotes a third magnetic body portion, and 54 denotes a coil.

4A is a perspective view of the coil structure shown through the third magnetic body portion 53 and the coil 54, FIG. 4B is a plan view of the coil structure, and FIG. 4 (c) is a side view of the coil structure. 5A schematically shows the magnetic flux (linkage magnetic flux) Φ ₀ for the coil 54, and FIG. 5B schematically shows the magnetic flux Φ ₀ for the coil structure.

  As shown in FIG. 4A to FIG. 4C, the coil structure of this example includes a first magnetic body portion 51, a second magnetic body portion 52 facing the first magnetic body portion 51, It has a third magnetic body portion 53 provided between the first magnetic body portion 51 and the second magnetic body portion 52, and a coil 54.

  The first magnetic body portion 51 and the second magnetic body portion 52 are each formed of, for example, a sheet-shaped soft magnetic material, and the third magnetic body portion 53 is formed of a substantially cylindrical soft magnetic material. . Here, the 1st magnetic body part 51, the 2nd magnetic body part 52, and the 3rd magnetic body part 53 can be integrally formed with the same soft magnetic material.

  Alternatively, they are formed independently, and for example, the cylindrical third magnetic body portion 53 is arranged between the first magnetic body portion 51 and the second magnetic body portion 52 (for example, substantially in the center). May be. In this case, for example, the material of the first and second magnetic parts 52 and 53 (soft magnetic material) and the material of the third magnetic part 53 can be different from each other.

  In the following description, for the sake of simplification, it is assumed that the first to third magnetic body portions 51 to 53 are all the same soft magnetic material (same permeability) and all have a circular planar shape. The first and second magnetic body parts 51 and 52 have the same size (area: projected area).

Here, as described with reference to FIG. 3, the efficiency (for example, power supply efficiency) kQ can be expressed as kQ = k × (Q ₁ Q ₂ ) ^1/2, and k = M ₁₂ / (L ₁ L ₂ ) ^1/2 , Q = (Q ₁ Q ₂ ) ^1/2 = ω (L ₁ L ₂ / R ₁ R ₂ ) ^1/2 , so kQ is expressed by the following equation (4). Is done.
kQ = ωM ₁₂ / (R ₁ R ₂ ) ^1/2 (4)

  Therefore, it can be seen that in order to increase the efficiency kQ, it is better to increase the mutual inductance M and decrease the coil resistance R.

As shown in FIG. 5A and FIG. 5B, the magnetic flux passing through (passing through, passing through) the first magnetic body portion 51 and the second magnetic body portion 52 is generated in the coil 54 (the first in the coil 54). 3 magnetic body portion 53). That is, as shown in FIGS. 5A and 5B, the flux linkage Φ ₀ is converged to the third magnetic body portion 53 (core) in the coil 54 to some extent.

First, the mutual inductance M is defined by the number of magnetic fluxes N ₂ Φ ₂ linked to the secondary circuit when the unit current I ₁ is passed through the primary circuit, and expressed as N ₂ Φ ₂ = MI ₁ . Here, the flux linkage in the coil 54 having an air core and an area S ₀ is Φ ₀ , the upper and lower areas (projected areas) of the first and second magnetic body portions 52 and 53 are S ₀ , and the first in the coil 54 The center area of the three magnetic part 53 is Sc. The magnetic permeability μc of the core is expressed as μc = αμ _0, and the length ratio (outer peripheral ratio) β of the first and second magnetic body portions 51 and 52 and the third magnetic body portion 53 is β = (Sc / S ₀ ) ^1/2 .

  Assuming that the magnetic flux passes up and down (vertical direction) through the first and second magnetic body portions 51 and 52, the vertical magnetic resistance (reluctance) is considered. In general, the reluctance Rm having an area of S and a magnetic permeability of μ is given by Rm∝1 / (μS).

In the coil structure of the present embodiment, the central portion is a parallel connection of the third magnetic body portion 53 and air (relative magnetic permeability 1), and the first and second magnetic body portions 51 having a relative magnetic permeability α above and below the third magnetic body portion 53, Assume that 52 are connected in series. In this case, it is considered that the magnetic flux Φc passing through the third magnetic body portion 53 in the coil 54 is α / (α + β ² −1) times Φ ₀ .
That is, Φc is expressed by the following equation (5).
Φc≈μcSc / [μ ₀ (S ₀ −Sc) + μc Sc] × Φ ₀
≒ α / [α + (β ² -1)] × Φ ₀ (5)

Therefore, the mutual inductance Mc (= M ₁₂ ) is expressed by the following equation (6).
Mc≈α / (α + β ² −1) (6)
As an example, when α = 100 and β = 10, Mc = 0.91M ₀ , and it can be seen that the mutual inductance is maintained at about 90% of the original, that is, about 10% can be reduced. The above description is based on a simple model. Needless to say, deviation from the magnetoresistive model can occur quantitatively due to the effect of the core shape or the like.

FIG. 6 is a diagram for explaining the reduction of the coil resistance by the coil structure of the present embodiment, and the relationship between the area Sc (coil diameter) of the coil 54 wound around the third magnetic body portion 53 and the resistance R is explained. Is to do. 6A shows a case where the area S of the coil 54 is large (S = S ₀ ), and FIG. 6B shows a case where the area S of the coil 54 is small (S = S ₀ / β ^2). ).

First, the coil resistance R is proportional to the wire length of the coil. Therefore, when the above-described resistance R ₀ of the air-core coil is used, the resistance R c of the coil 54 in the coil structure of the present embodiment is considered to be R ₀ / β. For example, when the beta = 10, the Rc = R _0/10. That is, when the coil area is reduced to 1/100, the coil resistance is reduced to 1/10.

  Therefore, for example, a case where the coil structure of the present embodiment is applied to one of the power transmitter 1 (power transmission resonance coil 11a) or the power receiver 2 (power reception resonance coil 21a) which will be described later with reference to FIGS. Think.

If the efficiency (power transmission / reception efficiency) kQ at this time is kcQc, kcQc is expressed by the following equation (7).
kcQc = ωMc / (R ₁ Rc) ^1/2
≈ωαM ₀ / (α + β ² −1) × (1 / [(R ₁ R ₀ ) / β] ^1/2
≈ (αβ ^1/2 ) / (α + β ² −1) × (ωM ₀ ) / (R ₁ R ₀ ) ^1/2
≒ (αβ ^1/2 ) / (α + β ² -1) x k ₀ Q ₀ (7)

Accordingly, kcQc can be considered to be approximately (αβ ^1/2 ) / (α + β ² −1) times k ₀ Q ₀ . As an example, when α = 100 and β = 10, kcQc≈2.9 k ₀ Q ₀ . That is, it can be seen that kQ can be increased to 2.9 times the original value. This is because, in the above-described formula (4), the denominator (R: (R ₁ R ₂ ) ^1/2 ) decreases more than the numerator (M: M ₁₂ ) decreases due to an increase in β. Can be described as

FIG. 7 is a diagram for explaining the effect of the present embodiment. In the above equation (7), when kcQc≈ (αβ ^1/2 ) / (α + β ² −1) × k ₀ Q ₀ , (αβ ^{1 / 2} ) / (α + β ² −1) = X (α, β), the horizontal axis represents the length ratio β of the narrowed portion, and the vertical axis represents the coefficient X. FIG. 7 shows various relative magnetic permeability α = 1 to 10000 and β dependency on Xmax.

  In other words, in FIG. 7, the characteristic curves CL1, CL2, CL3, CL4, CL5, CL6, CL7 are respectively obtained for α values 1,100, 200, 400, 600, 800, 1000, 2000, 5000, 10000 and Xmax. , CL8, CL9, CL10 and CL11.

  The description so far has been based on the case where the core loss is sufficiently small and can be ignored. However, FIG. 7 considers the case where there is a core loss. If there is a core loss, the coil resistance increases. Looks.

Here, assuming that the increase in the coil resistance due to the core loss is R ″, as shown in FIG. 7, the coil resistance Rc can be expressed as Rc = R ₀ / β ″, and kcQc at that time is αβ ″. ^1/2 / (α + β ² −1), which is (β ″ / β) ^1/2 times when there is no core loss.

As an example, when α = 100, β = 10, β ″ = 8, kcQc = 2.6 k ₀ Q _0. That is, αβ ^1/2 / (α + β ² −1)> (β ″ / β) ¹ If it is ^{/ 2} , it can be said that there is an effect of sufficiently increasing the efficiency kQ even if there is a core loss.

  Next, an example of a wireless power transmission system to which the present embodiment is applied will be described with reference to FIGS. 8 and 9, only one power transmitter 1 (wireless power transmission unit 11) and one power receiver 2 (wireless power reception unit 21) are illustrated, but in this embodiment, a plurality of power transmitters 1 are illustrated. As described above, the present invention can be applied to a wireless power transmission system including a plurality of power receivers 2.

  FIG. 8 is a block diagram schematically showing an example of a wireless power transmission system, in which reference numeral 1 indicates a primary side (power transmitter) and 2 indicates a secondary side (power receiver). As shown in FIG. 8, the power transmitter 1 includes a wireless power transmission unit 11, a high frequency power supply unit 12, a power transmission control unit 13, and a communication circuit unit (first communication circuit unit) 14. The power receiver 2 includes a wireless power reception unit 21, a power reception circuit unit (rectification unit) 22, a power reception control unit 23, and a communication circuit unit (second communication circuit unit) 24.

  The wireless power transmission unit 11 includes a power supply coil 11b and a power transmission resonance coil (power transmission coil) 11a, and the wireless power reception unit 21 includes a power reception resonance coil (power reception coil) 21a and a power extraction coil 21b.

  As illustrated in FIG. 8, the power transmitter 1 and the power receiver 2 transmit energy (electric power) from the power transmitter 1 to the power receiver 2 due to magnetic field resonance between the power transmission resonance coil 11 a and the power reception resonance coil 21 a, for example. Perform transmission.

  The power transmitter 1 and the power receiver 2 perform communication (short-distance communication) by the communication circuit unit 14 and the communication circuit unit 24. Here, the power transmission distance (power transmission range) by the power transmission resonance coil 11 a of the power transmitter 1 and the power reception resonance coil 21 a of the power receiver 2 is determined by the communication circuit unit 14 of the power transmitter 1 and the communication circuit unit 24 of the power receiver 2. It is set shorter than the communication distance (communication range).

  Moreover, the power transmission by the power transmission resonance coil 11a and the power reception resonance coil 21a is a method (Out-band communication) independent of the communication by the communication circuit units 14 and 24. Specifically, power transmission by the power transmission resonance coils 11a and 21a uses, for example, a frequency band of 6.78 MHz or 85 kHz, and communication by the communication circuit units 14 and 24 uses, for example, a frequency band of 2.4 GHz. .

  As communication by the communication circuit units 14 and 24, for example, a DSSS wireless LAN or Bluetooth (Bluetooth (registered trademark)) compliant with IEEE 802.11b can be used.

  In the wireless power transmission system described above, the power transmission resonance coil 11a of the power transmitter 1 and the power reception resonance coil of the power receiver 2, for example, in the near field at a distance of about 1/6 of the wavelength of the frequency to be used. Electric power is transmitted using magnetic field resonance by 21a. Therefore, the power transmission range (power transmission area) changes according to the frequency used for power transmission.

  The high-frequency power supply unit 12 supplies high-frequency power to the power supply coil 11b, and the power supply coil 11b uses electromagnetic induction with respect to the power transmission resonance coil 11a disposed in the vicinity of the power supply coil 11b. Supply power. The power transmission resonance coil 11a transmits power to the power reception resonance coil 21a (power receiver 2) at a power transmission frequency that causes magnetic field resonance with the power reception resonance coil 21a.

  The power reception resonance coil 21a supplies power to the power extraction coil 21b disposed in the vicinity of the power reception resonance coil 21a by using electromagnetic induction. A power receiving circuit unit 22 is connected to the power extraction coil 21b to extract predetermined power. Note that the power from the power receiving circuit unit 22 is used, for example, for charging a battery in the battery unit (load) 25 or as a power output for the circuit of the power receiver 2.

  Here, the high frequency power supply unit 12 of the power transmitter 1 is controlled by the power transmission control unit 13, and the power reception circuit unit 22 of the power receiver 2 is controlled by the power reception control unit 23. The power transmission control unit 13 and the power reception control unit 23 are connected via the communication circuit units 14 and 24, and various controls are performed so that power transmission from the power transmitter 1 to the power receiver 2 can be performed in a preferable state. Is supposed to do.

  FIG. 9 is a diagram for explaining a modification of the transmission coil in the wireless power transmission system of FIG. 8. FIGS. 9 (a) and 9 (b) show an example of a three-coil configuration. c) shows an example of a two-coil configuration.

  That is, in the wireless power transmission system shown in FIG. 8, the wireless power transmission unit 11 includes a power supply coil 11b and a power transmission resonance coil 11a, and the wireless power reception unit 21 includes a power reception resonance coil 21a and a power extraction coil 21b.

  On the other hand, in the example of FIG. 9 (a), the wireless power receiving unit 21 is one coil (power receiving resonance coil: LC resonator) 21a, and in the example of FIG. 9 (b), the wireless power transmitting unit 11 is one. The coil (power transmission resonance coil: LC resonator) 11a is used.

  Further, in the example of FIG. 9C, the wireless power receiving unit 21 is set as one power receiving resonance coil 21a, and the wireless power transmission unit 11 is set as one power transmission resonance coil 11a. 9A to 9C are merely examples, and it goes without saying that various modifications can be made.

  The coil structure of the present embodiment can be applied to, for example, at least one of the power transmission resonance coil 11a and the power reception resonance coil 21a in FIGS. 8 and 9 described above. That is, the coil structure of the present embodiment can be applied to only the power transmission resonance coil 11a, only the power reception resonance coil 21a, or both the power transmission resonance coil 11a and the power reception resonance coil 21a.

FIG. 10 is a diagram for explaining a first example of conditions in the coil structure according to the present embodiment. FIG. 10 (a) shows a plan view and FIG. 10 (b) shows a side view. First, as shown in FIG. 10A, the area (first projected area) Sc of the third magnetic body portion 53 in the coil 54, and the first magnetic body portion 51 and the second magnetic body portion 52. The ratio (Sc / S ₀ ) of the larger area (second projected area) S ₀ is obtained.

Next, as shown in FIG. 10B, the magnetic flux (first magnetic flux) Φc passing (transmitting) the third magnetic body portion 53 in the coil 54, the first magnetic body portion 51 and the second magnetic body. The ratio (Φc / Φ ₀ ) of the larger magnetic flux (second magnetic flux) Φ ₀ among the magnetic fluxes transmitted through the section 52 is obtained.

The ratio (Φc / Φ ₀ ) of the first magnetic flux Φc and the second magnetic flux Φ ₀ is the fourth root of the ratio (Sc / S ₀ ) of the first projected area Sc and the second projected area S ₀ ((Sc / It is specified that Φc / Φ ₀ > (Sc / S ₀ ) ^{−1/4, which} is a value larger than S ₀ ) ^−1/4 ). Note that (Sc / S ₀ ) ^−1/4 corresponds to β ^1/2 .

Thus, if Φc / Φ ₀ > (Sc / S ₀ ) ^−1/4 is defined, the value of kQ is larger than when the coil (54) having the same area of the air core is used. It will be a thing. Furthermore, as shown in FIG. 7 described above, for example, Φc / Φ ₀ > (Sc / S ₀ ) ^−1/4 × 1.5, that is, if it is defined to be larger than 1.5 times, A more sufficient kQ can be obtained.

In addition, in FIG. 10, although the case where the area of the 1st magnetic body part 51 and the 2 magnetic body part 52 differs was considered, if the 1st and 2nd magnetic body parts 51 and 52 are the same shape (same projection area), Needless to say, one of the areas is applied as S ₀ . The same applies to FIGS. 11 to 13 described below.

FIG. 11 is a diagram for explaining a second example of conditions in the coil structure according to the present embodiment, in which FIG. 11 (a) shows a plan view and FIG. 11 (b) shows a side view. First, as shown in FIG. 11A, the effective first resistance value Rc of the coil 54 and the larger one of the first magnetic body portion 51 and the second magnetic body portion 52 with the same wire as the coil 54. The square root (Rc / R ₀ ) ^−1/2 of the substantial second resistance value R ₀ of the air-core coil equal to is obtained.

That is, R ₀ is a resistance value in an air-core coil having a larger outer peripheral length among the first magnetic body portion 51 and the second magnetic body portion 52 by the same wire material (material, thickness, etc.) as that used for the coil 54. It corresponds to.

Next, as shown in FIG. 11 (b) (as described with reference to FIG. 10 (b)), the first magnetic flux Φc passing through the third magnetic body portion 53 in the coil 54, and the first The ratio (Φc / Φ ₀ ) of the larger second magnetic flux Φ ₀ among the magnetic fluxes transmitted through the magnetic body portion 51 and the second magnetic body portion 52 is obtained.

The ratio (Φc / Φ ₀ ) between the first magnetic flux Φc and the second magnetic flux Φ ₀ is larger than the square root (Rc / R ₀ ) ^{−1/2 of} the first resistance value Rc and the second resistance value R _0. It is specified that Φc / Φ ₀ > (Rc / R ₀ ) ^−1/2 holds. Note that (Rc / R ₀ ) ^−1/2 corresponds to β ^1/2 .

Thus, if it is defined that Φc / Φ ₀ > (Rc / R ₀ ) ^−1/2 holds, the value of kQ is larger than that when the coil (54) having the same area of the air core is used. It will be a thing. Further, for example, Φc / Φ ₀ > (Rc / R ₀ ) ^−1/2 × 1.5, that is, if it is specified to be larger than 1.5 times, a more sufficient kQ can be obtained. .

FIG. 12 is a diagram for explaining a third example of conditions in the coil structure according to the present embodiment. FIG. 12 (a) shows a plan view and FIG. 12 (b) shows a side view. As shown in FIG. 12A (as described with reference to FIG. 10A), the first projected area Sc of the third magnetic body portion 53 in the coil 54 and the first magnetic body portion 51 are shown. Then, the ratio (Sc / S ₀ ) of the second projected area S ₀ of the larger one of the second magnetic parts 52 is obtained.

Then, the square root (S ₀ / Sc) ^−1/2 of the reciprocal (S ₀ / Sc) of the ratio (Sc / S ₀ ) of the first projected area Sc to the second projected area S ₀ is 3 or more ((S ₀ / Sc) ^-1/2 ≧ 3) Here, (S ₀ / Sc) ^−1/2 corresponds to β.

That is, as shown in FIG. 7 described above, if (S ₀ / Sc) ^−1/2 ≧ 3, the effect of increasing kQ is considered sufficient, but 5 or more ((S ₀ / Sc) ^{− 1/2} ≧ 5) is even more preferable.

FIG. 13 is a diagram for explaining a fourth example of conditions in the coil structure according to the present embodiment, in which FIG. 13 (a) shows a plan view and FIG. 13 (b) shows a side view. As shown in FIGS. 13A and 13B, the first outer periphery (the line length of the coil 54) Lc of the third magnetic body portion 53, the first magnetic body portion 51, and the second magnetic body portion. The ratio (Lc / L ₀ ) of the larger second outer circumference L ₀ out of 52 is obtained.

Then, the ratio (Lc / L ₀ ) between the first outer periphery Lc and the second outer periphery L ₀ is defined to be 3 or more (Lc / L ₀ ≧ 3). Here, (Lc / L ₀ ) corresponds to β. That is, as in the case of FIG. 12 described above, if Lc / L ₀ ≧ 3, it is considered that the effect of increasing kQ is sufficient, but if it is 5 or more (Lc / L ₀ ≧ 5), it is even more effective. This is preferable.

  The first to fourth examples of the conditions for defining the coil structure according to the present embodiment described with reference to FIGS. 10 to 13 are, for example, the shape and size of the apparatus to which the coil structure is applied, or the handling. Depending on various factors such as electric power, allowable volume and weight, an appropriate one is used.

  FIG. 14 is a view for explaining an example of the third magnetic body portion in the coil structure of the present embodiment, and FIG. 14 (a) is a sectional view and a plan view of the entire coil structure. 14 (b) to 14 (d) are cross-sectional views showing the third magnetic body portion 53 and the coil 54 in an enlarged manner.

  FIG. 14B shows a state in which the third magnetic body portion 53 has a cylindrical shape, and the coil 54 is wound around the outside of the third magnetic body portion 53. The coil 54 may be helically wound a plurality of times so as to be in close contact with the outside of the third magnetic body portion 53, but may be wound spirally so that the coils 54 overlap each other.

  However, when the coil is wound in a helical shape, the area Sc of the third magnetic body portion 53 in the coil 54 where the magnetic fields of the first and second magnetic body portions 51 and 52 are narrowed does not change, but the coil is helical. When it is wound around, the substantial area Sc increases.

  14 (c) and 14 (d), the shape of the third magnetic body portion 53 is such that the central diameter around which the coil 54 is wound is smaller than both ends in contact with the first and second magnetic body portions 51, 52. In other words, the diameter of the third magnetic body portion 53 is formed so as to continuously change.

  That is, in order to helically wind the coil 54 around the third magnetic body portion 53 a plurality of times, the shape of FIG. 14A is preferable, but the coil 54 is placed once outside the third magnetic body portion 53. Alternatively, for winding in a spiral shape, FIGS. 14 (c) and 14 (d) are preferred.

  In order to narrow the magnetic field of the first and second magnetic body parts 51 and 52 to the third magnetic body part 53 in the coil 54, the first and second magnetic body parts 51 and 52 and the third magnetic body part 53 are used. This is because it is considered advantageous that the diameter (soft magnetic material) is continuously changed. Note that the shape of the third magnetic body portion shown in FIG. 14 is merely an example, and it goes without saying that various modifications and changes can be made.

  FIG. 15 is a diagram for explaining an example of the first magnetic body portion and the second magnetic body portion in the coil structure of the present embodiment, and FIG. 15 (e) corresponds to the basic shape described above, FIG. 15A to FIG. 15D correspond to modifications. FIG. 15 (e) also shows locations used for the simulation calculation conditions described later with reference to FIG. 16 and FIG.

  First, in the example shown in FIG. 15 (a), the first and second magnetic body portions 51 and 52 are asymmetrical shapes corresponding to the shape of a device (for example, a smartphone) to which the coil structure is applied. The example shown in FIG. 15 (c) has a substantially rectangular shape.

  That is, the 1st and 2nd magnetic body parts 51 and 52 can be made into substantially circular shape, elliptical shape, rectangular shape, polygonal shape, or asymmetrical shape, for example. Here, for example, when a rectangular shape or a polygonal shape is used, various modifications such as rounding corners are possible.

  In the example shown in FIG. 15B, the first and second magnetic parts 51 and 52 are formed with notches 50A, and the example shown in FIG. 15D shows the first and second magnetic parts. A slit 50 </ b> B is formed in the body parts 51 and 52. The slit 50B may be a dent (concave portion).

  As described above, even if the first and second magnetic parts 51 and 52 are not necessarily formed (filled) with the soft magnetic material, the effect of the coil structure according to this embodiment described above is exhibited. That is, when the coil structure of the present embodiment is applied to, for example, a power receiving resonance coil (21a) of a smartphone, the first and second magnets are formed by adopting the shapes shown in FIGS. 15 (b) and 15 (d). It is possible to reduce the weight by the body parts 51 and 52.

  In the above, it goes without saying that the first magnetic body portion 51 and the second magnetic body portion 52 do not have to have the same shape. Further, the shapes of the first and second magnetic parts shown in FIG. 15 are merely examples, and it goes without saying that various modifications and changes can be made.

  FIG. 16 and FIG. 17 are diagrams showing an example of simulation by the coil structure of this example, FIG. 16 (a) shows calculation conditions, FIG. 16 (b) shows simulation results, and FIG. Indicates various numerical values and kQ normalization in the simulation.

First, as shown in FIG. 15 (e), the thickness of the first and second magnetic parts 51, 52 is X, the thickness (height) of the third magnetic part 53 is Y, the first and first The diameter of the second magnetic parts 51 and 52 is D ₀ , and the diameter of the third magnetic part 53 in the coil 54 is Dc.

As shown in FIG. 16A, the calculation conditions for the simulation are as follows: the frequency f is 100 kHz, the relative magnetic permeability μr of the soft magnetic material is 1000, X is 5 mm, Y is 10 mm, and D ₀ is 100 mm. It was.

  The line width of the coil 54 was 1 mm, the wire thickness of the coil 54 (every time it was wound) was 0.1 mmt, the diameter of the power transmission coil was 500 mm, and the distance was 100 mm. The inner diameter of the coil 54 was set to twice the coil wire width (Dc + 2) with respect to the diameter Dc of the third magnetic body portion 53 in the coil 54.

FIG. 16B shows a simulation result in which the change in kQ is normalized when β (= D ₀ / Dc) is changed to 1, 2, 5, 10, 25 as shown in FIG. Further, FIG. 16B also shows the case of an air-core coil (μr = 1) to which this embodiment is not applied.

In FIG. 17, R ₁ is the resonance coil resistance (loss) of the power transmitter, R ₂ is the resonance coil resistance of the power receiver, L ₁ is the self-inductance of the power transmitter, L ₂ is the self-inductance of the power receiver, and M ₁₂ indicates the mutual inductance between the transmitter and the receiver. Q ₁ is the Q value of the transmitter (the degree of electromagnetic field loss), Q ₂ is the Q value of the receiver, k is the degree of electromagnetic field coupling, and kQ and the efficiency (power receiving efficiency) from FIG. can get.

As described above, in the simulation shown in FIGS. 16 and 17, the diameter D ₀ of the first and second magnetic body portions 51 and 52 is fixed to 100 mm, and the diameter Dc of the third magnetic body portion 53 in the coil 54 is changed. And kQ was calculated.

  As a result, as shown in FIG. 16 (b), compared with an air-core coil (when there is no narrowing), the coil structure of this example (the coil structure of this example is applied to a power receiving resonance coil). It can be seen that a larger kQ can be obtained according to the electric appliance).

  That is, by applying the present embodiment, it can be said that, for example, high efficiency can be achieved without increasing the thickness and outer diameter of the core. The above-described simulation is a case where the coil structure of the present embodiment is applied to a power receiving resonance coil (power receiver), but the same effect can be obtained when it is applied to a power transmission resonance coil (power transmitter). Needless to say.

  That is, the present embodiment can be applied to, for example, one of the resonance coil of the power transmitter and the resonance coil of the power receiver in the wireless power transmission system using magnetic field resonance, or both of the resonance coils.

  In the above description, the present embodiment is not limited to smartphones and laptop computers with received power of several watts to several tens of watts, but also for home appliances that handle large amounts of power, or power infrastructure equipment such as automobiles. Can be widely applied.

  Although the embodiment has been described above, all examples and conditions described herein are described for the purpose of helping understanding of the concept of the invention applied to the invention and the technology. It is not intended to limit the scope of the invention. Nor does such a description of the specification indicate an advantage or disadvantage of the invention. Although embodiments of the invention have been described in detail, it should be understood that various changes, substitutions and modifications can be made without departing from the spirit and scope of the invention.

Regarding the embodiment including the above examples, the following supplementary notes are further disclosed.
(Appendix 1)
A first magnetic body part;
A second magnetic body portion facing the first magnetic body portion;
A third magnetic body portion provided between the first magnetic body portion and the second magnetic body portion;
A coil wound around the third magnetic part,
The area of the third magnetic body part in the coil is smaller than the areas of the first magnetic body part and the second magnetic body part,
The coil structure characterized by the above-mentioned.

(Appendix 2)
The first magnetic body portion and the second magnetic body portion are each formed of a sheet-shaped soft magnetic material, and the third magnetic body portion is formed of a substantially cylindrical soft magnetic material,
Magnetic flux that passes through the first magnetic body part and the second magnetic body part is narrowed down to the third magnetic body part in the coil.
The coil structure according to Supplementary Note 1, wherein:

(Appendix 3)
The third magnetic body portion has a shape in which a central diameter around which the coil is wound is smaller than both ends in contact with the first magnetic body portion and the second magnetic body portion.
The coil structure according to appendix 1 or appendix 2, characterized in that.

(Appendix 4)
The first magnetic body part, the second magnetic body part, and the third magnetic body part are integrally formed.
The coil structure according to any one of supplementary notes 1 to 3, characterized in that:

(Appendix 5)
The ratio between the first magnetic flux that passes through the third magnetic body portion in the coil and the larger second magnetic flux among the magnetic fluxes that pass through the first magnetic body portion and the second magnetic body portion is within the coil. A value larger than the fourth root of the ratio of the first projected area of the third magnetic body portion and the larger second projected area of the first magnetic body portion and the second magnetic body portion,
The coil structure according to any one of supplementary notes 1 to 4, characterized in that:

(Appendix 6)
The ratio of the first magnetic flux that passes through the third magnetic body portion in the coil to the larger second magnetic flux of the magnetic flux that passes through the first magnetic body portion and the second magnetic body portion is An effective first resistance value and a value larger than the square root of the second resistance value of the air-core coil made equal to the larger one of the first magnetic part and the second magnetic part with the same wire as the coil Become
The coil structure according to any one of supplementary notes 1 to 4, characterized in that:

(Appendix 7)
The square root of the reciprocal of the ratio of the first projected area of the third magnetic body portion in the coil to the larger second projected area of the first magnetic body portion and the second magnetic body portion is 3 or more. ,
The coil structure according to any one of supplementary notes 1 to 4, characterized in that:

(Appendix 8)
The ratio of the first outer periphery of the third magnetic body portion to the larger second outer periphery of the first magnetic body portion and the second magnetic body portion is 3 or more.
The coil structure according to any one of supplementary notes 1 to 4, characterized in that:

(Appendix 9)
The first magnetic body part and the third magnetic body part are substantially circular, elliptical, rectangular, polygonal or asymmetrical,
The coil structure according to any one of supplementary notes 1 to 8, wherein the coil structure is characterized in that

(Appendix 10)
The first magnetic body part and the second magnetic body part have at least one slit, dent or notch,
The coil structure according to appendix 9, wherein

(Appendix 11)
A power transmitter including a power transmission resonance coil that wirelessly transmits power to a power receiver using magnetic field resonance,
The power transmission resonance coil is the coil structure according to any one of appendix 1 to appendix 10.
A power transmitter characterized by that.

(Appendix 12)
further,
A power supply coil for supplying power to the power transmission resonance coil using electromagnetic induction;
A high-frequency power supply for supplying high-frequency power to the power supply coil,
The power transmitter according to appendix 11, wherein

(Appendix 13)
further,
A communication circuit unit for communicating with the power receiver;
A power transmission control unit that controls the high-frequency power supply unit based on the output of the communication circuit unit,
The power transmitter according to appendix 12, characterized by:

(Appendix 14)
A power receiver including a power receiving resonance coil that receives power from a power transmitter wirelessly using magnetic field resonance,
The power receiving resonance coil is the coil structure according to any one of supplementary notes 1 to 10.
A power receiver characterized by that.

(Appendix 15)
further,
A power extraction coil for receiving power from the power receiving resonance coil using electromagnetic induction;
An internal circuit for receiving power extracted from the power extraction coil,
15. The power receiver according to appendix 14, wherein the power receiver is characterized in that

(Appendix 16)
further,
A communication circuit unit for communicating with the power transmitter;
A power reception control unit that controls the power reception resonance coil based on the output of the power extraction coil and the output of the communication circuit unit,
The power receiver as set forth in appendix 15, wherein

(Appendix 17)
A wireless power transfer system including at least one power transmitter and at least one power receiver,
At least one of the power transmitters is the power transmitter according to any one of appendix 11 to appendix 13, or
At least one of the power receivers is the power receiver according to any one of supplementary notes 14 to 16.
A wireless power transmission system.

1 Power transmitter (primary side: power transmission side)
1A1 to 1A3 Power transmitter 2 Power receiver (secondary side: power receiving side)
2A1-2A3, 2B1-2B3, 2C1, 2C2 Power receiver 11 Wireless power transmission unit 11a Power transmission resonance coil (LC resonator)
11b Power supply coil 12 High frequency power supply unit 13 Power transmission control unit 14 Communication circuit unit (first communication circuit unit)
21 Wireless power receiving unit 21a Power receiving resonance coil (LC resonator)
21b Power extraction coil 22 Power receiving circuit (rectifier)
23 Power reception control unit 24 Communication circuit unit (second communication circuit unit)
25 Battery (device body, load)
51 First Magnetic Part 52 Second Magnetic Part 53 Third Magnetic Part 54 Coil

Claims (11)

A first magnetic body part;
A second magnetic body portion facing the first magnetic body portion;
A third magnetic body portion provided between the first magnetic body portion and the second magnetic body portion;
A coil wound around the third magnetic part,
The area of the third magnetic body in the coil, rather smaller than the area of the first magnetic body and the second magnetic body,
The ratio between the first magnetic flux that passes through the third magnetic body portion in the coil and the larger second magnetic flux among the magnetic fluxes that pass through the first magnetic body portion and the second magnetic body portion is within the coil. A value larger than the fourth root of the ratio of the first projected area of the third magnetic body portion and the larger second projected area of the first magnetic body portion and the second magnetic body portion ,
The coil structure characterized by the above-mentioned. A first magnetic body part;
A second magnetic body portion facing the first magnetic body portion;
A third magnetic body portion provided between the first magnetic body portion and the second magnetic body portion;
A coil wound around the third magnetic part,
The area of the third magnetic body in the coil, rather smaller than the area of the first magnetic body and the second magnetic body,
The ratio of the first magnetic flux that passes through the third magnetic body portion in the coil to the larger second magnetic flux of the magnetic flux that passes through the first magnetic body portion and the second magnetic body portion is An effective first resistance value and a value larger than the square root of the second resistance value of the air-core coil made equal to the larger one of the first magnetic part and the second magnetic part with the same wire as the coil Become
The coil structure characterized by the above-mentioned. A first magnetic body part;
A second magnetic body portion facing the first magnetic body portion;
A third magnetic body portion provided between the first magnetic body portion and the second magnetic body portion;
A coil wound around the third magnetic part,
The area of the third magnetic body in the coil, rather smaller than the area of the first magnetic body and the second magnetic body,
The square root of the reciprocal of the ratio of the first projected area of the third magnetic body portion in the coil to the larger second projected area of the first magnetic body portion and the second magnetic body portion is 3 or more. ,
The coil structure characterized by the above-mentioned. A first magnetic body part;
A second magnetic body portion facing the first magnetic body portion;
A third magnetic body portion provided between the first magnetic body portion and the second magnetic body portion;
A coil wound around the third magnetic part,
The area of the third magnetic body in the coil, rather smaller than the area of the first magnetic body and the second magnetic body,
The ratio of the first outer periphery of the third magnetic body portion to the larger second outer periphery of the first magnetic body portion and the second magnetic body portion is 3 or more .
The coil structure characterized by the above-mentioned. The first magnetic body portion and the second magnetic body portion are each formed of a sheet-shaped soft magnetic material, and the third magnetic body portion is formed of a substantially cylindrical soft magnetic material,
Magnetic flux that passes through the first magnetic body part and the second magnetic body part is narrowed down to the third magnetic body part in the coil.
The coil structure according to any one of claims 1 to 4 , characterized in that: The third magnetic body portion has a shape in which a central diameter around which the coil is wound is smaller than both ends in contact with the first magnetic body portion and the second magnetic body portion.
The coil structure according to any one of claims 1 to 5, wherein: The first magnetic body part and the third magnetic body part are substantially circular, elliptical, rectangular, polygonal or asymmetrical,
The coil structure according to any one of claims 1 to 6 , wherein: The first magnetic body part and the second magnetic body part have at least one slit, dent or notch,
The coil structure according to claim 7 . A power transmitter including a power transmission resonance coil that wirelessly transmits power to a power receiver using magnetic field resonance,
The power transmission resonance coil is the coil structure according to any one of claims 1 to 8 .
A power transmitter characterized by that. A power receiver including a power receiving resonance coil that receives power from a power transmitter wirelessly using magnetic field resonance,
The power receiving resonance coil is the coil structure according to any one of claims 1 to 8 .
A power receiver characterized by that. A wireless power transfer system including at least one power transmitter and at least one power receiver,
At least one of the power transmitters is the power transmitter of claim 9 , or
At least one of the power receivers is a power receiver according to claim 10 .
A wireless power transmission system.

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