JP2017212830A - Wireless power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a wireless power transmission system that can perform efficient wireless power transmission even when an arrangement position of a power reception coil has moved, and generates little unnecessary radiation.SOLUTION: A wireless power transmission system includes: a power reception coil resonant circuit configured by connecting a power reception resonant capacitor and a load circuit to a power reception coil; a local relay resonant circuit configured by connecting a local resonant capacitor to a local relay coil; and power parallel supply means for supplying AC power to the local relay resonant circuit. A first resonant frequency between the local relay resonant circuit and the power reception coil resonant circuit at the time of the power reception coil being close to the local relay coil is made to differ from a second resonant frequency of the local relay resonant circuit at the time of the power reception coil not being close to the local relay coil. AC power having the first resonant frequency is supplied from the power parallel supply means; the local relay coil having been close to the power reception coil is taken as a relay path for transmitting the AC power to the power reception coil.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a wireless power transmission system that supplies power to an electric device across a space.

  A wireless power transmission system that feeds power to a power receiving coil that is opposed to a power transmitting coil with a space therebetween can transmit power without contacting the electrode terminal of the power supply device and the electrode terminal of the load device. There is an advantage that the problem of contact failure of the contact point where the contact is made does not occur. Taking advantage of this advantage, wireless power transmission systems are used for toothbrushes and mobile phones.

  Moreover, in patent document 1, a receiving coil and a power transmission coil are inductively coupled on a one-to-one basis by switching a plurality of power transmission coils installed according to the movement position of the electric vehicle with a switch and energizing the electric vehicle without contact. Wireless power transmission systems that transmit power have been proposed.

  Patent Document 2 proposes a wireless power transmission system that transmits power to an electric vehicle in a contactless manner using a long rectangular power transmission coil.

JP, 2014-082805, A JP, 2015-073381, A

  However, in Patent Document 1, since a switch circuit is required for wireless power transmission by inductively coupling the power receiving coil and the power transmission coil on a one-to-one basis, there is a problem that the cost of the wireless power transmission system increases.

  Moreover, in patent document 2, there existed a problem that many unnecessary radiations (radiation noise) generate | occur | produce from a power transmission coil by using a long power transmission coil.

  Therefore, a problem to be solved by the present invention is to construct a wireless power transmission system that can perform efficient wireless power transmission even when the arrangement position of the power receiving coil is moved and that has less unnecessary radiation.

  In order to solve this problem, the present invention has a power reception coil resonance circuit configured by connecting a power reception resonance capacitor to a power reception coil and connecting a load circuit, and connecting a local resonance capacitor to a local relay coil. A local relay resonance circuit configured, power parallel feeding means for supplying AC power to the local relay resonance circuit, and the local relay resonance circuit and the power reception when the power receiving coil approaches the local relay coil The first resonance frequency of the coil resonance circuit is made different from the second resonance frequency of the local relay resonance circuit when the power receiving coil is not approaching the local relay coil, The AC power having the first resonance frequency is fed, and the local relay coil approaching the power receiving coil is used as a relay path for transmitting the AC power to the power receiving coil. A wireless power transmission system according to symptoms.

  With this configuration, the present invention makes the AC power from the parallel power feeding means a main relay path that resonates the local relay coil that is close to the power receiving coil to flow current and transmits power to the power receiving coil resonance circuit. . That is, there is an effect that the local relay resonance circuit has a power transmission switch function. And since a resonance current mainly flows through the local relay coil approaching the power receiving coil and a current value flowing through the local relay coil not approaching the power receiving coil is small, there is an effect that unnecessary radiation can be reduced.

  The present invention is the above-described wireless power transmission system, characterized in that the parallel power feeding means has a power feeding relay coil that is inductively coupled to the local relay coil.

  Further, the present invention is the above wireless power transmission system, wherein the parallel power feeding means has an electrode terminal connected to the local relay resonance circuit, and a coupling capacitor is inserted in series with the electrode terminal. This is a wireless power transmission system.

  Further, the present invention is the above wireless power transmission system, wherein the parallel power feeding unit has an electrode terminal connected to the local relay resonance circuit, and a coupling inductance is inserted in series with the electrode terminal. This is a wireless power transmission system.

  Further, the present invention is the above wireless power transmission system, wherein the parallel power feeding means has an electrode terminal connected to the local relay resonance circuit, and a coupling capacitance and a coupling inductance are connected in series with the electrode terminal. A wireless power transmission system in which a parallel circuit is inserted.

  The wireless power transmission system of the present invention is a main relay that transmits AC power from the parallel power feeding means to the power receiving coil resonance circuit by causing the local relay coil close to the power receiving coil to resonate and causing a current to flow. On the road. That is, there is an effect that the local relay resonance circuit has a power transmission switch function.

  And since a current mainly flows through the local relay coil to which the power receiving coil approaches, the local relay coil through which a current mainly causing unnecessary radiation flows is limited to the local relay coil at the position of the power receiving coil. As a result, the main current flows in a region having a sufficiently small area as compared with a wide area where the power receiving coil can move, so that there is an effect that unnecessary radiation can be reduced.

1 is a schematic plan view showing a configuration of a wireless power transmission system according to a first embodiment of the present invention. 1 is a schematic side view showing a configuration of a wireless power transmission system according to a first embodiment of the present invention. It is an equivalent circuit of the wireless power transmission system of the first embodiment of the present invention. It is a graph of S parameter (S21) showing the wireless power transmission efficiency of the simulation result of the wireless power transmission system of Example 1 of the 1st Embodiment of this invention. It is a graph of the frequency characteristic of the electric current which flows into each local relay coil LM of Example 1 of the 1st Embodiment of this invention. It is a typical top view which shows the structure of the wireless power transmission system of the 2nd Embodiment of this invention. It is a graph of S parameter (S21) showing the wireless power transmission efficiency of the simulation result of the wireless power transmission system of Example 2 of the 2nd Embodiment of this invention. It is a graph of the frequency characteristic of the electric current which flows into each local relay coil LM of Example 2 of the 2nd Embodiment of this invention. It is a typical top view which shows the structure of the wireless power transmission system of the 3rd Embodiment of this invention. It is a graph of S parameter (S21) showing the wireless power transmission efficiency of the simulation result of the wireless power transmission system of Example 3 of the 3rd Embodiment of this invention. It is a graph of the frequency characteristic of the electric current which flows into each local relay coil LM of Example 3 of the 3rd Embodiment of this invention. It is a typical top view which shows the structure of the wireless power transmission system of the 4th Embodiment of this invention. It is a graph of S parameter (S21) showing the wireless power transmission efficiency of the simulation result of the wireless power transmission system of Example 4 of the 4th Embodiment of this invention. It is a graph of the frequency characteristic of the electric current which flows into each local relay coil LM of Example 4 of the 4th Embodiment of this invention. It is a typical top view which shows the structure of the wireless power transmission system of the 5th Embodiment of this invention. It is a graph of S parameter (S21) showing the wireless power transmission efficiency of the simulation result of the wireless power transmission system of Example 5 of the 5th Embodiment of this invention. It is a graph of the frequency characteristic of the electric current which flows into each local relay coil LM of Example 5 of the 5th Embodiment of this invention.

<First Embodiment>
(Configuration of wireless power transmission system)
The configuration of the wireless power transmission system of the first embodiment is shown in the plan view of FIG. 1 and the side view of FIG. FIG. 3 shows an equivalent circuit of the wireless power transmission system. As shown in FIG. 3, the wireless power transmission system of the first embodiment includes a power receiving coil resonance circuit 1 configured by connecting a power receiving resonance capacitor CU to a power receiving coil LU and a load circuit LD. The load circuit LD is connected in series or in parallel to the power receiving coil LU of the power receiving coil resonance circuit 1, and the load circuit LD consumes power.

(Receiving coil resonance circuit 1)
As shown in FIG. 3, the power receiving coil resonance circuit 1 is configured by connecting a power receiving resonance capacitor CU to a power receiving coil LU. A load circuit LD is connected in parallel or in series with the power reception resonance capacitor CU of the power reception coil resonance circuit 1. As shown in the side view of FIG. 2, the power receiving coil LU is arranged at a certain height h above the local relay coil LM arranged in the horizontal plane, and the power receiving coil LU is simultaneously arranged in a plurality of local areas as shown in FIG. The relay coil LM is brought close to and inductively coupled.

  The power receiving coil LU brought close to the plurality of local relay coils LM is moved from the position A to the position B in FIG. 1 while keeping the height h constant.

(Local relay resonance circuit 2)
Further, a plurality of local relay resonance circuits 2 configured by connecting a local resonance capacitor CM to the local relay coil LM are arranged as shown in FIG. Then, as shown in FIG. 3, a parallel power feeding means 3 for feeding AC power of a first resonance frequency f (described later) to the plurality of local relay resonance circuits 2 is provided.

(Parallel power feeding means 3)
As shown in FIG. 1, the parallel power feeding means 3 has a plurality of feeding relay coils LP that are inductively coupled to the local relay coils LM of each local relay resonance circuit 2, and the plurality of feeding relay coils LP are connected to the feeder line pair LA. Connect in parallel. A power supply circuit SC that supplies AC power is connected to the pair of feeder lines LA, and a shared capacitor CW is connected in parallel to the pair of feeder lines LA and combined with a plurality of relay coils LP for feeding a shared capacitor resonator. Configure.

(Shared capacity resonator)
As shown in FIG. 1, a plurality of power feeding relay coils LP <b> 1 to LP <b> 6 are provided in the parallel power feeding means 3 so as to be inductively coupled with the local relay coil LM of the local relay resonance circuit 2. The feed relay coils LP1 to LP6 are connected in parallel to the feed line pair LA. A shared capacitor CW is connected in parallel to the feed line pair LA, and a shared capacitor resonator is configured in combination with the feed relay coils LP1 to LP6.

  A power supply circuit SC is connected to the pair of power supply lines LA to supply AC power having a first resonance frequency f (described later) of the power supply circuit SC to the shared capacitor resonator. The AC power causes the local relay resonance circuit 2 to resonate by causing a current to flow through the plurality of feeding relay coils LP of the common capacity resonator and electromagnetically inducing the local relay coil LM.

  The shared capacitor resonator may be configured by directly connecting a plurality of feed relay coils LP in parallel to the shared capacitor CW in which the power supply circuit SC is connected in parallel, without using the feed line pair LA. . In the configuration in which the power supply circuit SC is connected in parallel to the shared capacitor CW, the value of the output impedance of the power supply circuit SC that matches the impedance of the circuit is high.

  In the parallel power feeding means 3 of the present embodiment, the power supply circuit SC is connected in parallel to the shared capacitor CW of the shared capacitor resonator, so that the output impedance value of the power supply circuit SC that matches impedance with the shared capacitor resonator is increased. become.

(Feeding line pair LA)
When the power supply line pair LA is used to supply power to the power supply relay coil LP of the shared capacity resonator, the power supply line pair in the case where currents in opposite directions flow through the power supply lines LA1 and LA2 of the power supply line pair LA. It is desirable to reduce the self-inductance of LA. For this purpose, it is possible to use a pair of power supply lines LA in which the surfaces of two power supply lines LA1 and LA2 having a strip or coaxial cylindrical surface are opposed in parallel.

  Further, the plurality of feeding relay coils LP of the shared capacitance resonator may have different shapes and self-inductances. Even if all the self-inductances of the power supply relay coils LP are different, the power supply relay coils LP share the capacity of the shared capacitor CW, and all the power supply relay coils LP resonate at the same resonance frequency, thereby transmitting wireless power. Can be executed with high efficiency.

(Change in resonance frequency due to inductive coupling of power receiving coil LU and local relay coil LM)
In the present embodiment, as shown in FIG. 1, the power receiving coil LU is simultaneously approached and inductively coupled to the plurality of local relay coils LM. For example, the local relay coil LM is installed on a horizontal plane, the power receiving coil LU is installed in a horizontal plane parallel to the local relay coil LM, and is opposed to the local relay coil LM in parallel. As shown in the side view of FIG. 2, the distance between the two coils is made to approach and be inductively coupled at a height of a distance h equal to or less than the diameter of the power receiving coil LU.

(First resonance frequency and second resonance frequency)
When the power reception coil LU approaches the local relay coil LM, the resonance frequency f of the local relay resonance circuit 2 (and the power reception coil resonance circuit 1) including the local relay coil LM is defined as a first resonance frequency. On the other hand, a unique resonance frequency when the local relay resonance circuit 2 including the local relay coil LM that does not approach the power receiving coil LU exists alone is defined as a second resonance frequency.

  In the present invention, the first resonance frequency of the local relay resonance circuit 2 including the local relay coil LM close to the power receiving coil LU is equal to the inherent resonance of the local relay resonance circuit 2 including the local relay coil LM not close to the power receiving coil LU. A phenomenon that deviates from the second resonance frequency, which is a frequency, is used.

  The reason why the first resonance frequency of the local relay resonance circuit 2 deviates from the second resonance frequency is that the magnetic field generated by the power receiving coil LU through which the resonance current flows is electromagnetically induced in the local relay coil LM close to the power receiving coil LU. This is because the voltage is generated to change the resonance frequency of the local relay resonance circuit 2 including the local relay coil LM.

(The resonance frequency of the shared capacitor resonator is adjusted to the first resonance frequency.)
From the power supply circuit SC, AC power having the first resonance frequency f is supplied to the shared capacitance resonator of the parallel power feeding means 3. The shared capacity resonator of the parallel power feeding means 3 determines the capacity of the shared capacity CW and the inductances of the plurality of power feeding relay coils LP connected in parallel so as to resonate at the first resonance frequency f.

  As a result, the shared capacitor resonator resonates due to the AC power of the first resonance frequency f from the power supply circuit SC, AC flows through the power supply relay coil LP, and the AC of the power supply relay coil LP becomes the local relay coil LM. Electromagnetic induction.

(Switch function of local relay coil LM)
Since the resonance frequency of the local relay resonance circuit 2 including the local relay coil LM is the first resonance frequency f in the local relay coil LM that is close to the power receiving coil LU, a resonance current flows through the local relay coil LM.

  On the other hand, in the local relay coil LM that the power receiving coil LU does not approach, the second resonance frequency, which is a specific resonance frequency of the local relay resonance circuit 2 including the local relay coil LM, is an alternating current fed from the power supply circuit SC. Since it is different from the first resonance frequency f of power, the current flowing through the local relay coil LM is reduced.

  As described above, the second resonance frequency, which is the inherent resonance frequency of the local relay resonance circuit 2 including the local relay coil LM that is not close to the power receiving coil LU, is set to the first AC power supplied from the power supply circuit SC. 1 is different from the resonance frequency f. Thereby, the AC power of the first resonance frequency f from the power supply circuit SC is transmitted to the power receiving coil LU using the local relay coil LM to which the power receiving coil LU approaches as a main relay path.

  As a result, the local relay coil LM can have a switching function in which the local relay coil LM to which the power receiving coil LU approaches is a main relay path for electric power. Then, the load circuit LD of the power receiving coil resonance circuit 1 including the power receiving coil LU that has received AC power consumes the power.

  A switching function was obtained in which the local relay resonance circuit 2 of the local relay coil LM close to the power receiving coil LU becomes the main relay path for power. This switching function is achieved by the resonance frequency of the local relay resonance circuit 2 including the local relay coil LM approaching the power receiving coil LU, due to the electromagnetic induction of the magnetic field generated by the current flowing through the power receiving coil LU. This is achieved by changing from the resonance frequency (second resonance frequency) to the first resonance frequency.

  In fact, there is a law that (current flowing through the local relay coil LM2) / (current flowing through the local relay coil LM6) increases as (current flowing through the power receiving coil LU) / (current flowing through the local relay coil LM2) increases. Therefore, in order to increase the current flowing through the local relay coil LM2 approached by the power receiving coil LU, that is, to increase the ratio of (current flowing through the local relay coil LM2) / (current flowing through the local relay coil LM6), the power receiving coil It is necessary to adjust so as to increase the resonance current flowing through the LU.

  The local relay coil LM to which the power receiving coil LU approaches becomes a main relay path for electric power, and a current flows mainly through the local relay coil LM. Therefore, a local relay coil LM in which a current that mainly causes unnecessary radiation flows flows. However, there exists an effect limited to the local relay coil LM with which the receiving coil LU approached. As a result, the current that becomes a source of unnecessary radiation is mainly current in a region having a sufficiently small area as compared with the area of all the local relay coils LM, and there is an effect that unnecessary radiation can be reduced.

(Power supply circuit SC)
It is desirable to make the output impedance of the power supply circuit SC equal to the input impedance of the circuit of the wireless power transmission system observed from the power supply circuit SC side in order to match the impedance of the circuit of the wireless power transmission system and transmit power efficiently. .

  This condition can also be realized by using a power supply circuit SC using a constant voltage power supply or a constant current power supply with sufficiently small output impedance. The reason is that the power supply circuit SC constituted by a constant voltage power supply or a constant current power supply having a sufficiently small output impedance has a power supply circuit having an output impedance equal to the input impedance of the circuit of the wireless power transmission system observed from the power supply circuit SC side. This is because the operation is equivalent.

  When the constant voltage power supply having a sufficiently small output impedance is the power supply circuit SC, when the imaginary component (reactance) of the input impedance of the circuit observed from the power supply circuit SC side is sufficiently smaller than the real component, the constant voltage power supply The power supply circuit SC supplies a current inversely proportional to the real component of the input impedance of the circuit. In that case, the power supply circuit SC has an output impedance equal to the input impedance of the circuit, and is equivalent to a power supply circuit in which the internal voltage source has a voltage twice the output voltage. That is, it is equivalent to a power supply circuit whose output impedance is equal to the input impedance of the circuit and whose impedance is matched.

  When the imaginary component of the input impedance of the circuit is small, most of the power output from the power supply circuit SC, that is, the product of voltage and current is effective power, and most of the effective power is effectively consumed by the load circuit LD. Is done. Therefore, a constant voltage power source or a constant current power source having a sufficiently small output impedance is used as the power supply circuit SC, and the power circuit SC is used under the condition that the imaginary component (reactance) of the input impedance of the circuit observed from the power circuit SC side is sufficiently smaller than the real component. Thus, there is an effect that the wireless power transmission efficiency of the wireless power transmission system can be improved.

(When load circuit LD has rectifier circuit and charging capacitor)
When the load circuit LD is composed of a rectifier circuit and a charging capacitor or capacitor connected to the rectifier circuit, the load circuit LD is considered to operate as follows. In the initial state in which the capacitor for charging the load circuit LD is not charged, the capacitor for charging having a large capacity of the load circuit LD can be regarded as a load having an impedance close to 0 and a small impedance.

  Next, when the charging capacitor is charged, the current rectified by the rectifying circuit of the load circuit LD can no longer flow into the charging capacitor, and the charging capacitor of the load circuit LD is considered to have changed to a load having a large impedance. I think I can do it. As described above, since the load of the load circuit LD changes as the charging capacitor is charged, it is desirable to perform control to change the current for charging the charging capacitor accordingly.

(Modification 1)
As a first modification of the present embodiment, a power supply circuit SC connected to a shared capacitor resonator is connected in series or in parallel to a local relay resonance circuit 2 configured by a resonance capacitor and a local relay coil LM, and the local relay coil LM is connected. Can be opposed to one of the power supply relay coils LP to wirelessly supply the AC power of the power supply circuit SC to the shared capacitor resonator.

(Modification 2)
As a second modification of the present embodiment, the power supply circuit SC can be connected in series to one of the feeding relay coils LP of the shared capacitance resonator to supply AC power of the power supply circuit SC to the shared capacitance resonator.

(Modification 3)
As a third modification of the present embodiment, a plurality of power receiving coil resonance circuits 1 in which a load circuit LD, a power receiving coil LU, and a power receiving resonance capacitor CU are combined are prepared, and AC power is simultaneously supplied to the plurality of power receiving coil resonance circuits 1. A wireless power transmission system can be configured.

  Each receiving coil LU of the plurality of receiving coil resonance circuits 1 is inductively coupled by being brought close to a group of feeding relay coils LP at a plurality of positions of the shared capacitive resonator. From the parallel power feeding means 3, the plurality of power feeding relay coils LP of the common capacity resonator constituted by the capacity of the common capacity CW connected to the power supply circuit SC and a plurality of power feeding relay coils LP connected in parallel to the same. The power can be supplied by electromagnetic induction in parallel with the power receiving coil LU of the power receiving coil resonance circuit 1.

(Modification 4)
As a fourth modification of the present embodiment, the loop wiring is drawn out from the local relay coil LM of each local relay resonance circuit 2 and is inductively coupled to one power supply relay coil LP of the power parallel feeding means 3 so as to receive power. It can also be configured. That is, it is possible to configure a wireless power transmission system that feeds power from one feeding relay coil LP of the parallel power feeding means 3 to the plurality of local relay resonance circuits 2.

Example 1
As shown in FIG. 1, the wireless power transmission system according to Example 1 of the first embodiment includes a receiving coil resonance circuit configured by connecting a loop-shaped receiving coil LU, a receiving resonance capacitor CU, and a load circuit LD in series. 1, a plurality of local relay resonance circuits 2, and a parallel power feeding means 3 that feeds AC power having a first resonance frequency f to the plurality of local relay resonance circuits 2. The operation of this wireless power transmission system was investigated by electromagnetic field simulation.

(Receiving coil resonance circuit 1)
In the power receiving coil resonance circuit 1 of the first embodiment, a power receiving resonance capacitor CU is connected to the power receiving coil LU to form a resonance circuit, and a load circuit LD is connected in parallel to the power receiving resonance capacitor CU to consume power. .

(Receiving coil LU)
As shown in FIG. 2, the power receiving coil LU is arranged at a height h = 200 mm above the local relay coil LM arranged in the horizontal plane. As shown in FIG. 1, one power receiving coil LU is brought close to a plurality of local relay coils LM and inductively coupled. As the power receiving coil LU, a rectangular coil having a size of 2425 mm × 900 mm formed by a copper strip having a width of 25 mm and a thickness of 0.5 mm was used. This coil has a self-inductance of 6 μH. A power receiving resonance capacitor 1 is connected to the power receiving coil LU to form a power receiving coil resonance circuit 1. The capacitance of the power receiving resonance capacitor CU was 0.67 μF, and the unique resonance frequency of the power receiving coil resonance circuit 1 alone was 79 kHz.

(Local relay coil LM)
As shown in FIG. 1, the local relay coil LM of the local relay resonance circuit 2 is a rectangle having a coil surface dimension of 900 mm × 900 mm formed of a copper band having a coil wiring width of 25 mm and a thickness of 0.5 mm. A one-turn coil was used. This coil has a self-inductance of 3 μH. A local resonance capacitor 2 was configured by connecting a local resonance capacitor CM to the local relay coil LM. The capacitance of the local resonance capacitor CM was 1.18 μF, and the unique resonance frequency of the local relay resonance circuit 2 alone was set to 85 kHz. This resonance frequency 85 kHz is the second resonance frequency.

  Here, the second resonance frequency of 85 kHz of the local relay resonance circuit 2 is higher than the resonance frequency of 79 kHz alone of the power reception coil resonance circuit 1, but the second resonance frequency of the local relay resonance circuit 2 is set to the power reception coil resonance circuit. The wireless power transmission system can also be configured with the same resonance frequency as that of 1 alone. As described above, the second resonance frequency of the local relay resonance circuit 2 has a degree of freedom of setting.

  As shown in FIG. 1, the local relay coils LM1 to LM6 of the plurality of local relay resonance circuits 2 are arranged side by side at a pitch of 950 mm in one direction. The power supply relay coil LP of the shared capacitance resonator of the power parallel power supply means 3 was inductively coupled to the local relay coil LM of each local relay resonance circuit 2.

(Feeding line pair LA)
The power supply line pair LA of the power parallel power supply unit 3 according to the first embodiment includes a power supply line LA1 and a power supply line LA2. The feeder lines LA1 and LA2 are copper strip-like feeder lines LA1 and LA2 having a width of 50 mm and a thickness of 0.5 mm. The surfaces of the power supply lines LA1 and LA2 are made to face each other in parallel, and the distance between the surfaces of the power supply lines is set to 1 mm or less of 1/50 of the surface width of 50 mm, thereby configuring the power supply line pair LA. By doing so, the self-inductance of each feeder line of the feeder line pair LA can be made sufficiently smaller than the inductance of the feeding relay coil LP of the shared capacitance resonator.

(Power supply relay coil LP)
As shown in FIG. 1, the relay coils LP1 to LP6 for power feeding of the parallel power feeding means 3 have a coil surface dimension of 550 mm × the width of the coil wiring is 25 mm and the thickness is 0.5 mm. It was formed with a 125 mm rectangular one-turn coil. This coil has a self-inductance of 1 μH.

  The single resonance frequency of the shared capacitor resonator composed of the shared capacitor CW and the feeding relay coils LP1 to LP6 is 90 kHz when the shared capacitor CW is 19 μF, and 98 kHz when the shared capacitor CW is 16 μF. Became. There was no significant difference in the final results using either type of shared capacitance resonator. This result shows that the resonance frequency of the shared capacitor resonator does not necessarily need to coincide with the first resonance frequency f of AC power used for wireless power transmission (97.5 kHz obtained by simulation). means.

  It is desirable to adjust the resonance frequency of the shared capacitor resonator alone in accordance with the first resonance frequency f of AC power for wireless power transmission. The first resonance frequency f is a resonance frequency when the local relay resonance circuit 2 and the power receiving coil resonance circuit 1 are inductively coupled. Therefore, the shared capacitance CW of the shared capacitance resonator is set to 16 μF, and the shared capacitance resonator is resonated at 98 kHz close to the first resonance frequency f of AC power for wireless power transmission.

(simulation result)
The graph of FIG. 4 shows a graph of frequency characteristics in which the wireless power transmission efficiency as a result of the electromagnetic field simulation of Example 1 is represented by an S parameter (S21). In this simulation, the power receiving coil LU brought close to the plurality of local relay coils LM was moved 3075 mm from the position A to the position B of the set of local relay resonance circuits 2 in FIG. At that time, the height h = 200 mm from the local relay coil LM was kept constant.

  In the present embodiment, the local relay coil LM is used as a relay path having a switch function, and the resonance current flowing through the power receiving coil LU is increased in order to fully exhibit the switch function. Therefore, the ratio of (input impedance R2 of load circuit LD) / (output impedance R1 of power supply circuit SC) is increased so that output impedance R1 of power supply circuit SC is 0.24Ω, and input impedance R2 of load circuit LD is 26Ω.

  As a result of the simulation, as shown in the S parameter graph of FIG. 4, when the frequency f of the AC power of the power supply circuit SC is 97.5 kHz, the transmission efficiency of the power transmitted to the load circuit LD is −0.9 dB. It was. That is, the transmission efficiency was 80%. This transmission efficiency can be greatly improved by enlarging the coil width 25 mm, reducing the coil resistance, and reducing the resistance loss of the coil, so that wireless power transmission can be performed efficiently. This frequency 97.5 kHz is the first resonance frequency f.

  Further, even when the power receiving coil LU is moved 3075 mm from the position A to the position B, the wireless power transmission efficiency is hardly changed, and there is an effect that the wireless power transmission can be performed efficiently regardless of the position of the power receiving coil LU.

  The graph of FIG. 5 shows a graph of the current flowing through each local relay coil LM at the arrangement position A of the power receiving coil LU. This graph shows the current value when the frequency of the AC power of the power supply circuit SC is 90 kHz to 105 kHz. From the graph of FIG. 5, at a frequency of 97.5 kHz, the current flowing through the local relay coil LM6 not approached by the power receiving coil LU is about 18 dB less than the current flowing through the local relay coil LM2 approached by the power receiving coil LU. Decreased to about one-eighth. As a result, the energy of unnecessary radiation of the local relay coil LM6 is reduced to about 1/63 of the energy of unnecessary radiation due to the current of the local relay coil LM2.

  In the wireless power transmission system of the present embodiment, when the output impedance R1 of the power supply circuit SC is 0.24Ω and the input impedance R2 of the load circuit LD is 26Ω, the current of the local relay coil LM approaching the power receiving coil LU is obtained. The current of the other local relay coil LM is reduced to about 1/8. For this reason, it can be said that a main current flows through the local relay coil LM close to the power receiving coil LU. And the electric power from the feeding relay coil LP of the shared capacitance resonator is mainly supplied to the local relay coil LM through which a current flows.

  That is, among the local relay resonance circuits 2 between the power supply relay coil LP and the power reception coil LU, the local relay resonance circuit 2 to which the power reception coil LU approaches becomes a main relay path for transmitting power, and other local relay resonance circuits 2 The relay resonance circuit 2 functions as a switch that does not become a relay path. Thus, since the power receiving coil LU is not close, the resonance current flowing through the local relay coil LM that does not become a relay path is small, and therefore unnecessary radiation is reduced. Thus, the local relay coil LM that mainly generates unwanted radiation has the effect of being limited to the local relay coil LM close to the power receiving coil LU.

  Thereby, the wireless power transmission system of the present embodiment can wirelessly transmit power by arranging the power receiving coil LU at an arbitrary position in a wide area over the positions where all the local relay coils LM exist. In addition, since the portion where the current causing the unnecessary radiation mainly flows in the wide area is limited to the narrow area of the local relay coil LM close to the power receiving coil LU, there is an effect that the unnecessary radiation can be reduced.

<Second Embodiment>
(Configuration of wireless power transmission system)
FIG. 6 shows a plan view of the configuration of the wireless power transmission system of the second embodiment. As in the first embodiment, the wireless power transmission system according to the second embodiment includes a power receiving coil resonance circuit 1, a plurality of local relay resonance circuits 2, and the local relay resonance circuit 2 to the first relay resonance circuit 2. It has power parallel feeding means 3 for feeding AC power having a resonance frequency.

(Parallel power feeding means 3)
The second embodiment differs from the first embodiment in that, as shown in FIG. 6, an electrode terminal in which a coupling capacitor CP is inserted in series is pulled out in parallel with the feed line pair LA of the parallel power feeding means 3 and is locally By connecting in parallel to the local resonance capacitor CM of the relay resonance circuit 2, it is capacitively coupled to the electrode terminal of the local resonance capacitor CM of the local relay resonance circuit 2. Further, there is a feature in that a resonance circuit constituted by a shared capacitor CW and a shared inductance LW is connected in parallel to a power supply line pair LA connected to a power supply circuit SC that supplies AC power of frequency f.

  As shown in FIG. 6, the coupling capacitor CP has a plurality of electrode terminals drawn in parallel with the shared capacitor CW and the shared inductance LW as electrode plates, and the electrode plates are used as electrode plates constituting the local resonance capacitor CM. By making them face each other in parallel, it is possible to form a coupling capacitance CP coupled to the electrode plate of the local resonance capacitor CM. Alternatively, the coupling capacitor CP can be incorporated by inserting an external capacitor for the coupling capacitor CP in series with the electrode terminal and connecting the electrode terminal to the electrode terminal of the local resonance capacitor CM.

(Modification 5)
In the fifth modification of the parallel power feeding means 3 of the present embodiment, a plurality of sets of local shared inductances and local shared capacitors are connected in parallel to the feed line pair LA to form the entire shared inductance LW and shared capacitor CW. To do. For example, a set of local shared inductance and local shared capacity is connected in parallel to the feeder line pair LA for each local relay resonance circuit 2. Further, one set of local shared inductance and local shared capacitance can be connected in parallel to the feeder pair LA for each of the plurality of local relay resonance circuits 2.

  In the fifth modification, a power source of a local shared inductance and a local shared capacity is installed in the vicinity of the local relay resonance circuit 2 in this way, so that each local relay resonance circuit 2 has a power source of a nearby set. Is supplied with power. Thereby, the length of the wiring from the power source to the local relay resonance circuit 2 is substantially shortened, and the power loss due to the current of the wiring is reduced.

  In the wireless power transmission system of the second embodiment, the first resonance frequency of the power receiving coil resonance circuit 1 is changed when the power supply circuit SC approaches the power parallel power feeding means 3 and the power receiving coil LU approaches the local relay coil LM. AC power having a resonance frequency f is fed. The parallel power feeding means 3 feeds the AC power to each local relay resonance circuit 2 through capacitive coupling. Further, the resonance circuit of the parallel power feeding means 3 constituted by the shared capacitor CW and the shared inductance LW determines the capacitance of the shared capacitor CW and the inductance of the shared inductance LW so as to resonate at the first resonance frequency f.

  At that time, when the power receiving coil LU approaches the local relay coil LM, the resonance frequency of the local relay resonance circuit 2 including the local relay coil LM becomes the first AC power fed from the power parallel feeding means 3. It corresponds to the resonance frequency f. Therefore, power is fed from the parallel power feeding means 3 to the local relay resonance circuit 2 by capacitive coupling.

  On the other hand, the second resonance frequency that is a specific resonance frequency of the local relay resonance circuit 2 including the local relay coil LM that the power receiving coil LU does not approach is the first resonance of the AC power fed from the power parallel feeding unit 3. Unlike the frequency f, no resonance current flows through the local relay coil LM, and the power parallel feeding means 3 does not feed power to the local relay resonance circuit 2.

  In this way, the first resonance frequency f of the AC power supplied from the power supply circuit SC is set to the second resonance frequency that is the inherent resonance frequency of the local relay resonance circuit 2 including the local relay coil LM that the power receiving coil LU is not approaching. Thus, the AC power from the power supply circuit SC is transmitted to the power receiving coil resonance circuit 1 using the local relay coil LM close to the power receiving coil LU as a main relay path. The load circuit LD connected to the power receiving coil resonance circuit 1 consumes the power.

(Example 2)
Example 2 of the wireless power transmission system of the second embodiment is shown in the plan view of FIG. As shown in FIG. 6, the second embodiment uses the same receiving coil resonance circuit 1 and a plurality of local relay resonance circuits 2 as those in the first embodiment. In the second embodiment, the parallel power feeding means 3 having a plurality of electrode terminals that are capacitively coupled to the plurality of local relay resonance circuits 2 by the coupling capacitance CP is used. The power parallel feeding means 3 feeds AC power having the first resonance frequency f to the local relay resonance circuit 2 through the coupling capacitor CP.

  As shown in FIG. 6, the parallel power feeding means 3 has a resonance circuit composed of a shared capacitor CW and a shared inductance LW, and a power supply circuit SC and a feed line pair LA are connected in parallel to the resonance circuit. A plurality of electrode terminals were drawn out from the pair of power supply lines LA parallel to the resonance circuit, and the electrode terminals were capacitively coupled to the local resonance capacitors CM1 to CM6 of each local relay resonance circuit 2.

  In this capacitive coupling, the tip of the electrode terminal is used as an electrode plate, and the electrode plate is placed in parallel with the electrode plate constituting the local resonance capacitor CM to form a coupling capacitance CP. In FIG. 6, capacitive coupling is represented by coupling capacitances CP1 to CP6. The operation of this wireless power transmission system was investigated by electromagnetic field simulation.

(Receiving coil LU)
The receiving coil resonance circuit 1 of the second embodiment is a rectangular winding coil having a size of 2425 mm × 900 mm formed of a copper strip having a width of 25 mm and a thickness of 0.5 mm, which has the same shape as that of the first embodiment. LU was used. This power receiving coil LU has a self-inductance of 6 μH. The power receiving coil LU was arranged at a height h = 200 mm above the local relay coil LM.

  In the second embodiment, in order to make the unique resonance frequency of the receiving coil resonance circuit 1 the same as the unique resonance frequency 85 kHz of the local relay resonance circuit 2, a receiving resonance capacitor CU having a capacitance of 0.58 μF is provided in the receiving coil LU. Connected. Here, there is no problem even if the unique resonance frequency of the receiving coil resonance circuit 1 is different from the unique resonance frequency of the local relay resonance circuit 2, and there is a degree of freedom in setting the inductance of the receiving coil LU and the capacitance of the receiving resonance capacitor CU. There is.

(Local relay coil LM)
The local relay coil LM of the local relay resonance circuit 2 of the second embodiment has the same shape as the local relay coil LM of the first embodiment, and the width of the coil wiring is 25 mm and the thickness is 0.5 mm as shown in FIG. A rectangular one-turn coil formed of a copper strip and having a coil surface size of 900 mm × 900 mm was used. This local relay coil LM has a self-inductance of 3 μH. The local relay resonance circuit 2 is configured by connecting a local resonance capacitor CM having a capacitance of 1.18 μF to the local relay coil LM, and a second resonance frequency which is a unique resonance frequency of the local relay resonance circuit 2 alone. Was set to 85 kHz.

  As shown in FIG. 6, the local relay coils LM1 to LM6 of the plurality of local relay resonance circuits 2 are arranged side by side at a pitch of 950 mm in one direction. To the local resonance capacitors CM1 to CM6 of each local relay resonance circuit 2, coupling capacitors CP1 to CP6 of electrode terminals of the parallel power feeding means 3 were connected. As a result, the local resonance capacitors CM1 to CM6 are capacitively coupled to the resonance circuit constituted by the shared capacitor CW and the shared inductance LW of the parallel power feeding means 3 via the coupling capacitors CP1 to CP6.

(Parallel power feeding means 3)
In Example 2, as shown in FIG. 6, a resonant circuit configured by a shared capacitor CW and a shared inductance LW is installed in the parallel power feeding unit 3. As shown in FIG. 6, the shared inductance LW is formed by a rectangular one-turn coil having a coil surface width of 400 mm × 425 mm formed by a copper strip having a width of 25 mm and a thickness of 0.5 mm. . This coil has a self-inductance of 1.1 μH. A resonant circuit that resonates at 97 kHz was formed by connecting a shared capacitor CW of 2.5 μF to the shared inductance LW.

  A plurality of electrode terminals in parallel with the resonance circuit were capacitively coupled to face the local resonance capacitors CM1 to CM6 of each local relay resonance circuit 2. As a result, a coupling capacitance CP was formed between the electrode terminal and the local resonance capacitor CM. The capacity of the coupling capacity CP was 0.05 μF.

  Considering an equivalent circuit, electrode terminals drawn in parallel from the shared capacitor CW are connected to local resonance capacitors CM1 to CM6, and coupling capacitors CP1 to CP6 are connected to the electrode terminals connected to the local resonance capacitors CM1 to CM6. It becomes the circuit which inserted. Thus, the shared capacitor CW was capacitively coupled to the local resonance capacitors CM1 to CM6 via the coupling capacitors CP1 to CP6.

  A power supply line pair LA is connected in parallel to the resonance circuit constituted by the shared capacitor CW and the common inductance LW, and the power supply circuit SC is connected to the power supply line pair LA so that the AC power of the first resonance frequency f is supplied from the power supply circuit SC. The resonant circuit was powered. The feeder lines LA1 and LA2 constituting the feeder line pair LA are parallel to each other with the surfaces of the copper strip-like feeder lines LA1 and LA2 having a width of 200 mm and a thickness of 0.5 mm facing each other. Is set to 1 mm or less of 1/200 of the width of the surface of 200 mm to form the feeder line pair LA. By doing so, the self-inductance of each feeder line of the feeder line pair LA is sufficiently smaller than the shared inductance LW.

(simulation result)
The graph of FIG. 7 shows a graph of frequency characteristics in which the wireless power transmission efficiency as a result of the electromagnetic field simulation of Example 2 is represented by the S parameter (S21). In this simulation, the power receiving coil LU brought close to the plurality of local relay coils LM was moved 3075 mm from the position A to the position B of the set of local relay resonance circuits 2 in FIG. At that time, the height h = 200 mm from the local relay coil LM was kept constant.

  In this embodiment, the output impedance R1 of the power supply circuit SC is 16Ω, and the input impedance R2 of the load circuit LD is 30Ω.

  As a result of the simulation, as shown in the graph of the S parameter in FIG. 7, when the frequency f of the AC power of the power supply circuit SC is 96.5 kHz, the transmission efficiency of the power transmitted to the load circuit LD is −0.5 dB. It was. That is, the transmission efficiency was 89%. It is considered that this transmission efficiency can be greatly improved by increasing the coil width 25 mm to reduce the coil resistance and reducing the resistance loss of the coil. This frequency 96.5 kHz is the first resonance frequency f.

  Further, even when the power receiving coil LU is moved 3075 mm from the position A to the position B, the wireless power transmission efficiency is hardly changed, and there is an effect that the wireless power transmission can be performed efficiently regardless of the position of the power receiving coil LU.

  The graph of FIG. 8 shows a graph of the current flowing through each local relay coil LM at the arrangement position A of the power receiving coil LU. This graph shows the current value when the frequency of the AC power of the power supply circuit SC is 90 kHz to 105 kHz.

  From the graph of FIG. 8, in the wireless power transmission system of the present embodiment, the receiving coil LU has a frequency of 96.5 kHz under the condition that the output impedance R1 of the power supply circuit SC is 16Ω and the input impedance R2 of the load circuit LD is 30Ω. The current that flows in the local relay coil LM6 that the power receiving coil LU does not approach is about 12 dB less than the current that flows in the local relay coil LM2 that approaches.

  That is, the current of the local relay coils LM other than the local relay coil LM approaching the power receiving coil LU is reduced to about one-fourth. Therefore, among the plurality of local relay resonance circuits 2 in which the plurality of electrode terminals of the power parallel feeding means 3 are capacitively coupled, the local relay resonance circuit 2 to which the power receiving coil LU is approached mainly transmits AC power to the power receiving coil LU. The other local relay resonance circuit 2 functions as a switch that does not become a main relay path.

  And the energy of the unnecessary radiation of the local relay coil LM6 with respect to the energy of the unnecessary radiation due to the current of the local relay coil LM2 is weak to about 1/16. That is, since the power receiving coil LU is not approaching, the resonance current flowing through the local relay coil LM that does not become a relay path is small. Therefore, the local relay coil LM that mainly generates unwanted radiation is connected to the local relay coil LM that the power receiving coil LU approaches. There are limited effects.

  Thereby, the wireless power transmission system of the present embodiment can transmit the power wirelessly by arranging the power receiving coil LU in a wide area extending over the positions where all the local relay coils LM exist. In addition, since the portion where the current causing the unnecessary radiation mainly flows in the wide area is limited to the narrow area of the local relay coil LM close to the power receiving coil LU, there is an effect that the unnecessary radiation can be reduced.

  In Example 2, the shared capacity CW used for the parallel power feeding unit 3 was 2.5 μF, and a smaller capacity than the 16 μF shared capacity CW used in Example 1 of the first embodiment was used. As in the second embodiment, the second embodiment can reduce the capacity of the shared capacitor CW used for the parallel power feeding means 3 and thus has an effect of reducing the manufacturing cost of the shared capacitor CW.

  Also in the second embodiment, the first resonance frequency f of the local relay resonance circuit 2 (and the power reception coil resonance circuit 1) including the local relay coil LM when the power reception coil LU approaches the local relay coil LM is A phenomenon that deviates from the second resonance frequency, which is an inherent resonance frequency when the relay resonance circuit 2 exists alone, is used. This is because the magnetic field generated by the power receiving coil LU in which the resonance current of the first resonance frequency f is generated electromagnetically induces a voltage in the local relay coil LM close to the power receiving coil LU, thereby generating the local relay. This is caused by changing the resonance frequency of the local relay resonance circuit 2 including the coil LM.

  In the first embodiment and the second embodiment, as shown in FIG. 3, AC power having the first resonance frequency f is supplied from the power supply circuit SC to the parallel power supply unit 3. The power parallel feeding means 3 feeds the AC power of the frequency f to the local relay coil LM through inductive coupling or capacitive coupling. Then, a main relay path in which a resonance current of the first resonance frequency f is mainly induced in the local relay coil LM approaching the power receiving coil LU, and the local relay coil LM transmits wireless power to the power receiving coil resonance circuit 1. become. In other words, the local relay coil LM is a wireless power transmission system that functions as a switch in which ON / OFF of relaying of AC power is controlled depending on whether or not the power receiving coil LU is approaching.

<Third Embodiment>
(Configuration of wireless power transmission system)
FIG. 9 shows a plan view of the configuration of the wireless power transmission system of the third embodiment. As in the first embodiment, the wireless power transmission system according to the third embodiment includes a power receiving coil resonance circuit 1, a plurality of local relay resonance circuits 2, and the local relay resonance circuit 2 to the first relay resonance circuit 2. It has power parallel feeding means 3 for feeding AC power having a resonance frequency.

(Parallel power feeding means 3)
The third embodiment is different from the previous embodiment in that an electrode terminal in which a parallel circuit of a coupling capacitor Cc and a coupling inductance Lc is inserted in series is pulled out in parallel with the power supply line pair LA of the parallel power feeding means 3 and locally. The point is that the local resonance capacitor CM of the relay resonance circuit 2 is connected in parallel. In addition, a resonance circuit composed of the common capacitor CW and the common inductance LW or the feeding relay coil LP is not used.

  Thus, power is supplied from the power supply circuit SC to the local relay resonance circuit 2 through the electrode terminal into which the parallel circuit of the coupling capacitor Cc and the coupling inductance Lc is inserted via the feeder line pair LA.

  In the wireless power transmission system according to the third embodiment, for example, as shown in FIG. 9, a set of a parallel circuit of a coupling capacitor Cc1 and a coupling inductance Lc1 is inserted in series with the electrode terminal drawn from the feeder line pair LA. The electrode terminal is connected in parallel to the local resonance capacitor CM1 of the first local relay resonance circuit 2.

  An electrode terminal in which a parallel circuit of a coupling capacitor Cc2 and a coupling inductance Lc2 is inserted in series is connected in parallel to the local resonance capacitor CM2 of the second local relay resonance circuit 2. Subsequently, a parallel circuit of a coupling capacitor Cc3 and a coupling inductance Lc3 is inserted in series into an electrode terminal connected in parallel to the local resonance capacitor CM3, and a coupling capacitor Cc4 is connected to an electrode terminal connected in parallel to the local resonance capacitor CM4. A parallel circuit of the coupling inductance Lc4 is inserted in series, a parallel circuit of the coupling capacitor Cc5 and the coupling inductance Lc5 is inserted in series at the electrode terminal connected in parallel to the local resonance capacitor CM5, and is connected in parallel to the local resonance capacitor CM6. A parallel circuit of a coupling capacitor Cc6 and a coupling inductance Lc6 is inserted in series into the electrode terminal to be connected.

  In the wireless power transmission system of the third embodiment, the resonance frequency of the power reception coil resonance circuit that has changed when the power reception coil LU approaches the local relay coil LM is defined as the first resonance frequency f, and the power supply circuit SC is the first power supply circuit SC. Each local relay resonance circuit 2 is fed through a parallel circuit of a coupling capacitor Cc and a coupling inductance Lc in which AC power having a resonance frequency f is fed to the parallel power feeding means 3 and the parallel power feeding means 3 connects the AC power to the electrode terminals in series. Power to

  Thereby, when the power receiving coil LU approaches the local relay coil LM, the resonance frequency f of the local relay resonance circuit 2 including the local relay coil LM is the first resonance frequency f fed from the parallel power feeding means 3. The AC power and frequency match. Therefore, power is fed from the parallel power feeding means 3 to the local relay resonance circuit 2 that resonates at the first resonance frequency f via the coupling capacitor Cc and the coupling inductance Lc.

  On the other hand, the second resonance frequency that is a specific resonance frequency of the local relay resonance circuit 2 including the local relay coil LM that the power receiving coil LU does not approach is the first resonance of the AC power fed from the power parallel feeding unit 3. The frequency is different from the frequency f. Therefore, the local relay resonance circuit 2 does not resonate at the first resonance frequency f, and the current flowing through the local relay coil LM is reduced.

  In this way, the first resonance frequency f of the AC power supplied from the power supply circuit SC is set to the second resonance frequency that is the inherent resonance frequency of the local relay resonance circuit 2 including the local relay coil LM that the power receiving coil LU is not approaching. Thus, AC power from the power supply circuit SC is supplied to the power receiving coil resonance circuit 1 using the local relay coil LM close to the power receiving coil LU as a main relay path. The load circuit LD connected to the power receiving coil resonance circuit 1 consumes the power.

(Example 3)
Example 3 of the wireless power transmission system according to the third embodiment is shown in the plan view of FIG. As shown in FIG. 9, a receiving coil resonance circuit 1 configured by connecting a loop-shaped receiving coil LU, a receiving resonance capacitor CU, and a load circuit LD in series, a plurality of local relay resonance circuits 2, and a plurality of local relay resonance circuits 2 Power parallel feeding means 3 for feeding AC power having the first resonance frequency f to the relay resonance circuit 2 is provided. The operation of this wireless power transmission system was investigated by electromagnetic field simulation.

(Receiving coil LU)
In the third embodiment, the receiving coil LU of the receiving coil resonance circuit 1 is a rectangular coil having a size of 2800 mm × 900 mm and formed of a copper strip having a width of 100 mm and a thickness of 0.5 mm. Was used. The power receiving coil LU has a self inductance of 4.5 μH. The capacity of the power reception resonance capacitor CU connected to the power reception coil LU was 1.04 μF, and the unique resonance frequency of the power reception coil resonance circuit 1 alone was 74 kHz.

(Local relay coil LM)
The local relay coil LM of the local relay resonance circuit 2 according to the third embodiment is a copper strip having a coil wiring width of 50 mm and a thickness of 0.5 mm, and a coil having a rectangular surface dimension of 900 mm × 900 mm. A coil was used. This local relay coil LM has a self-inductance of 2.4 μH. The capacitance of the local resonance capacitor CM connected to the local relay coil LM was set to 1.48 μF, and the local resonance frequency of the local relay resonance circuit 2 alone was set to 85 kHz. This resonance frequency 85 kHz is the second resonance frequency.

  As shown in FIG. 9, the local relay coils LM1 to LM6 of the plurality of local relay resonance circuits 2 are arranged side by side at a pitch of 1000 mm in one direction.

(Parallel power feeding means 3)
As shown in FIG. 9, the parallel power feeding means 3 of the third embodiment draws the belt-like feeder lines LA1 and LA2 in parallel with the electrode terminals from a pair of feeder lines LA formed with the strip surfaces facing each other in parallel. The local resonance capacitor CM of the resonance circuit 2 is connected in parallel. A parallel circuit of a coupling capacitor Cc and a coupling inductance Lc was inserted in series with the electrode terminal. The coupling capacitance Cc was 0.2 μF, the coupling inductance Lc was 50 μH, and the resonance frequency of the circuit of the coupling capacitance Cc and the coupling inductance Lc was 50 kHz.

(simulation result)
The graph of FIG. 10 shows a graph of frequency characteristics in which the wireless power transmission efficiency as a result of the electromagnetic field simulation of Example 3 is represented by the S parameter (S21). In this simulation, the power receiving coil LU brought close to a plurality of local relay coils LM is kept constant at a height h = 200 mm from the local relay coil LM from position A to position B of the set of local relay resonance circuits 2 in FIG. It was moved while keeping

  In this embodiment, the output impedance R1 of the power supply circuit SC is 2Ω, and the input impedance R2 of the load circuit LD is 10Ω.

  As a result of the simulation, as shown in the S parameter graph of FIG. 10, when the frequency f of the AC power of the power supply circuit SC is 91.6 kHz, the transmission efficiency of the power transmitted to the load circuit LD is −0.35 dB. It was. That is, the power transmission efficiency was 92%. 91.6 kHz is the first resonance frequency. The power transmission efficiency of 92% is considered to be able to further increase the power transmission efficiency by increasing the coil width to reduce the coil resistance to reduce the resistance loss of the coil.

  Further, even when the power receiving coil LU is moved from the position A to the position B, the wireless power transmission efficiency is hardly changed, and there is an effect that the wireless power transmission can be performed efficiently regardless of the position of the power receiving coil LU.

  The graph of FIG. 11 shows a graph comparing the current flowing through the local relay coils LM3 and LM6 when the power receiving coil LU is arranged at a position centered on the local relay coil LM3. This graph shows the current value of the local relay coil LM when the frequency of the AC power of the power supply circuit SC is changed from 80 kHz to 95 kHz.

  From the graph of FIG. 11, when the AC power of 91.6 kHz having the first resonance frequency is supplied from the power supply circuit SC, the power receiving coil LU is compared with the current value flowing through the local relay coil LM3 that the power receiving coil LU approaches. The value of the current flowing through the local relay coil LM6 that is not approaching is about 13 dB less. That is, the value of the current flowing through the local relay coil LM6 where the power receiving coil LU is not approaching is as small as about 1/4. As a result, the energy of unnecessary radiation due to the current of the local relay coil LM6 not approaching the power receiving coil LU is reduced to about 1/20 of the energy of unnecessary radiation due to the current of the local relay coil LM3.

  In addition to the configuration of the wireless power transmission system according to the third embodiment, when a 6 μH common inductance LW for connecting the feeders LA1 and LA2 of the feeder pair LA is added as in the second embodiment, the current flows to the local relay coil LM6. The frequency characteristic of the current is stabilized so that the current value is minimized at the first resonance frequency.

  The wireless power transmission system according to the third embodiment also includes a local relay resonance including a local relay coil LM that is close to the power receiving coil LU among the plurality of local relay resonance circuits 2 to which a plurality of electrode terminals of the parallel power feeding unit 3 are coupled. The circuit 2 becomes a main relay path that transmits AC power to the power receiving coil LU, and the other local relay resonance circuit 2 functions as a switch that does not become a relay path. Since the power receiving coil LU is not close, the current flowing through the local relay coil LM that does not become the main relay path is small, so that there is an effect of reducing unnecessary radiation that is generated.

  In the wireless power transmission system according to the third embodiment, many local relay coils LM can be arranged in a wide area where the power receiving coil LU can move. When such a large number of local relay coils LM are arranged to transmit power to the receiving coil LU wirelessly, the receiving coil LU is close to the portion where the current that causes unnecessary radiation flows mainly in the wide area. The local relay coil LM is limited to a narrow region of the group. Therefore, there is an effect that unnecessary radiation generated can be reduced even if a large number of local relay coils LM are arranged.

  In addition, the wireless power transmission system according to the third embodiment has a sufficient switching function for the local relay resonance circuit 2 even when the input impedance R2 of the load circuit LD connected in parallel to the power reception coil resonance circuit 1 is set to a lower 10Ω. There was an effect that could be demonstrated. When the input impedance R2 of the load circuit LD connected in parallel to the power receiving coil resonance circuit 1 is lowered, the resonance current flowing through the power receiving coil LU is reduced. The present embodiment has an effect that a sufficient switching function can be exhibited even if the resonance current flowing through the power receiving coil LU is reduced.

<Fourth Embodiment>
(Configuration of wireless power transmission system)
FIG. 12 is a plan view of the configuration of the wireless power transmission system according to the fourth embodiment. As in the third embodiment, the wireless power transmission system according to the fourth embodiment draws out a plurality of electrode terminals in parallel from the power supply line pair LA of the power parallel feeding means 3, and the electrode terminals are connected to a plurality of local relay resonance circuits. Two local resonance capacitors CM1 to CM6 are connected in parallel.

(Parallel power feeding means 3)
A first feature that the fourth embodiment differs from the other embodiments is that, as shown in FIG. 12, only the coupling capacitor Cc is inserted in series into the electrode terminals drawn in parallel from the parallel power feeding means 3. This configuration is a configuration in which the shared capacitor CW and the shared inductance LW are removed from the second embodiment, and the coupling capacitor Cc corresponds to the coupling capacitor CP of the second embodiment.

  The second feature of the fourth embodiment that is different from the other embodiments is that, in the fourth embodiment, the power receiving coil LU is made smaller and only one local relay coil LM is opposed to it. .

  That is, the power receiving coil LU is configured so as not to face a plurality of local relay coils LM at the same time, and the power receiving coil LU receives power in a one-to-one relationship with one local relay coil LM.

  The electrode terminal having the coupling capacitor Cc inserted in series is pulled out in parallel from the pair of power supply lines LA of the parallel power feeding means 3 and connected in parallel to the local resonance capacitor CM of the local relay resonance circuit 2, whereby the local relay resonance circuit 2 to supply power.

  The local resonance capacitor CM and the local relay coil LM constitute the local relay resonance circuit 2. The number of the local relay resonance circuits 2 may be only one, or a plurality of local relay resonance circuits 2 are connected in parallel to the feeder line pair LA via the electrode terminals into which the coupling capacitors Cc1 are inserted as shown in FIG. You may do it.

  In the wireless power transmission system of the fourth embodiment, the resonance frequency of the power reception coil resonance circuit that has changed when the power reception coil LU approaches the local relay coil LM is set to the first resonance frequency f, and the power supply circuit SC is the first power supply circuit SC. AC power having a resonance frequency f is supplied to the parallel power feeding means 3, and the parallel power feeding means 3 feeds each local relay resonance circuit 2 through the coupling capacitor Cc connected in series with the electrode terminal.

  Thus, when the power receiving coil LU approaches the local relay coil LM, the resonance frequency of the local relay resonance circuit 2 including the local relay coil LM is equal to the first resonance frequency f fed from the power parallel feeding unit 3. AC power and frequency match. Therefore, power is fed from the parallel power feeding means 3 to the local relay resonance circuit 2 that resonates at the first resonance frequency f via the coupling capacitor Cc.

  On the other hand, the second resonance frequency that is a specific resonance frequency of the local relay resonance circuit 2 including the local relay coil LM that the power receiving coil LU does not approach is the first resonance of the AC power fed from the power parallel feeding unit 3. The frequency is different from the frequency f. Therefore, the local relay resonance circuit 2 does not resonate at the first resonance frequency f, and the current flowing through the local relay coil LM is reduced.

  In this way, the first resonance frequency f of the AC power supplied from the power supply circuit SC is set to the second resonance frequency that is the inherent resonance frequency of the local relay resonance circuit 2 including the local relay coil LM that the power receiving coil LU is not approaching. Thus, the AC power from the power supply circuit SC is transmitted to the power receiving coil resonance circuit 1 using the local relay coil LM close to the power receiving coil LU as a main relay path. The load circuit LD connected to the power receiving coil resonance circuit 1 consumes the power.

Example 4
Example 4 of the wireless power transmission system according to the fourth embodiment is shown in the plan view of FIG. As shown in FIG. 12, a receiving coil resonance circuit 1 configured by connecting a loop-shaped receiving coil LU, a receiving resonance capacitor CU, and a load circuit LD in parallel, six local relay resonance circuits 2, and the local relay resonance thereof. Power parallel feeding means 3 for feeding AC power of the first resonance frequency f to the circuit 2 is provided. The operation of this wireless power transmission system was investigated by electromagnetic field simulation.

(Local relay coil LM)
The local relay coil LM of the local relay resonance circuit 2 according to the fourth embodiment is a copper strip having a coil wiring width of 200 mm and a thickness of 0.5 mm, and a coil having a rectangular surface dimension of 900 mm × 900 mm. A coil was used. This local relay coil LM has a self-inductance of 1 μH. The capacitance of the local resonance capacitor CM connected to the local relay coil LM was set to 3.4 μF, and the unique resonance frequency of the local relay resonance circuit 2 alone was set to 85 kHz. This resonance frequency 85 kHz is the second resonance frequency.

(Parallel power feeding means 3)
As shown in FIG. 12, the parallel power feeding means 3 of the fourth embodiment draws out electrode terminals in parallel from a pair of feeding lines LA formed with the belt-like feeding lines LA1 and LA2 facing each other in parallel. The local resonance capacitor CM of the relay resonance circuit 2 was connected in parallel. A coupling capacitor Cc was inserted in series with the electrode terminal. The coupling capacitance Cc was 1 μF.

(Receiving coil LU)
In the fourth embodiment, the receiving coil LU of the receiving coil resonance circuit 1 is a rectangular coil having the same shape as the local relay coil LM and having a size of 900 mm × 900 mm. This power receiving coil LU has a self-inductance of 1 μH. The capacitance of the power receiving resonance capacitor CU connected to the power receiving coil LU is set to 4 μF in order to match the impedance of the circuit well, and the specific resonance frequency of the power receiving coil resonance circuit 1 alone is set to 80 kHz.

(simulation result)
The graph of FIG. 13 shows a graph of frequency characteristics in which the wireless power transmission efficiency as a result of the electromagnetic field simulation of Example 4 is represented by the S parameter (S21). In this embodiment, the output impedance R1 of the power supply circuit SC is set to 0.85Ω, and the input impedance R2 of the load circuit LD is set to 10Ω.

  As a result of the simulation, as shown in the S parameter graph of FIG. 13, when the frequency f of the AC power of the power supply circuit SC is 87.6 kHz, the transmission efficiency of the power transmitted to the load circuit LD is −0.21 dB. It was. That is, the power transmission efficiency was 95%. 87.6 kHz is the first resonance frequency. This 95% power transmission efficiency can be further increased by further increasing the coil width to reduce the coil resistance to reduce the coil resistance loss.

  The graph of FIG. 14 shows a graph comparing the current flowing through the local relay coil LM with the power receiving coil LU approached and the current flowing through the local relay coil LM with the power receiving coil LU not approached. This graph is a graph in which the current value of the local relay coil LM in each case is relatively compared when the frequency of the AC power of the power supply circuit SC is changed from 60 kHz to 110 kHz.

  From the graph of FIG. 14, when AC power of 87.6 kHz having the first resonance frequency is supplied from the power supply circuit SC, the power receiving coil LU is larger than the current value flowing through the local relay coil LM6 that is not approaching the power receiving coil LU. The value of the current flowing through the local relay coil LM1 approaching is larger by 10 dB or more. That is, the value of the current flowing through the local relay coil LM1 close to the power receiving coil LU is three times larger than the value of the current flowing through the local relay coil LM6. And the energy of the unnecessary radiation by the electric current of the local relay coil LM6 which the receiving coil LU is not approaching becomes weak.

  In the graph of FIG. 14, at the first resonance frequency of 87.6 kHz, the current value flowing through the power receiving coil LU and the current value flowing through the local relay coil LM1 have the same magnitude. At the first resonance frequency, the current flowing through the power receiving coil LU and the current flowing through the local relay coil LM1 flow in opposite directions on the parallel coil wiring. Therefore, the unnecessary radiation generated by the current flowing through the power receiving coil LU and the unnecessary radiation generated by the current flowing through the local relay coil LM1 weaken each other, and there is an effect of reducing unnecessary radiation in the entire system.

  The wireless power transmission system according to the fourth embodiment also includes a local relay resonance including the local relay coil LM1 close to the power receiving coil LU among the plurality of local relay resonance circuits 2 to which the plurality of electrode terminals of the parallel power feeding unit 3 are coupled. The circuit 2 serves as a main relay path that transmits AC power to the power receiving coil LU, and the other local relay resonance circuit 2 functions as a switch that does not become a relay path. Since the power receiving coil LU is not close, the resonance current flowing through the local relay coil LM that does not become a relay path is small, so that there is an effect of reducing unnecessary radiation that is generated.

  Further, the current Imo that flows through the local relay coil LM when the power receiving coil LU does not exist is smaller than the current that flows through the local relay coil LM1 that the power receiving coil LU approaches. In this manner, a wireless power transmission system having a switching function in which the resonance current flowing through the local relay coil LM increases when the power receiving coil LU approaches the local relay coil LM can be configured.

(Modification 6)
In addition, the wireless power transmission system can be configured with only one local relay resonance circuit 2 according to the fourth embodiment. That is, a wireless power transmission system having only one local relay coil LM is configured.

  In this case, in order to match the impedance of the circuit well, the capacity of the power receiving resonance capacitor CU connected to the power receiving coil LU is set to 3.4 μF, and the specific resonance frequency of the power receiving coil resonant circuit 1 alone is set to 85 kHz. It is desirable.

  In that case, when the frequency f of the AC power of the power supply circuit SC was 92.4 kHz, the transmission efficiency of the power transmitted to the load circuit LD was −0.13 dB. That is, the power transmission efficiency was 97%. 92.4 kHz is the first resonance frequency.

  In addition, a wireless power transmission system having a switching function in which the resonance current flowing through the local relay coil LM increases when the power receiving coil LU approaches the local relay coil LM could be configured.

<Fifth Embodiment>
(Configuration of wireless power transmission system)
FIG. 15 is a plan view of the configuration of the wireless power transmission system of the fifth embodiment. As in the fourth embodiment, the wireless power transmission system according to the fifth embodiment has one local relay coil LM opposed to the power receiving coil LU, and one-to-one the local relay coil LM and the power receiving coil LU. Make them face each other.

(Parallel power feeding means 3)
The fifth embodiment is different from the fourth embodiment in that only the coupling inductance Lc is inserted in series with the electrode terminals drawn in parallel from the power parallel feeding means 3. In the fifth embodiment, a wireless power transmission system is configured using one or a plurality of local relay resonance circuits 2.

(Example 5)
In Example 5 of the fifth embodiment, the number of local relay resonance circuits 2 is one. That is, a wireless power transmission system having only one local relay coil LM is configured.

  As the power receiving coil LU and the local relay coil LM of the fifth embodiment, a rectangular one-turn coil having the same shape as that of the fourth embodiment and having a size of 900 mm × 900 mm was used. This power receiving coil LU has a self-inductance of 1 μH. The capacitance of the local resonance capacitor CM connected to the local relay coil LM was set to 3.4 μF, and the unique resonance frequency of the local relay resonance circuit 2 alone was set to 85 kHz. This resonance frequency 85 kHz is the second resonance frequency.

  Further, in order to match the impedance of the circuit well, the capacity of the power receiving resonance capacitor CU connected to the power receiving coil LU is set to 3.4 μF, and the specific resonance frequency of the power receiving coil resonant circuit 1 alone is set to 85 kHz.

(Parallel power feeding means 3)
In the power parallel feeding unit 3 of the fifth embodiment, the coupling inductance Lc inserted in series with the electrode terminals drawn in parallel from the power parallel feeding unit 3 is set to 35 μH.

(simulation result)
The graph of FIG. 16 shows a graph of frequency characteristics in which the wireless power transmission efficiency as a result of the electromagnetic field simulation of Example 5 is represented by the S parameter (S21). In this embodiment, the output impedance R1 of the power supply circuit SC is 3Ω, and the input impedance R2 of the load circuit LD is 10Ω.

  As a result of the simulation, as shown in the S parameter graph of FIG. 16, when the frequency f of the AC power of the power supply circuit SC is 97 kHz, the transmission efficiency of the power transmitted to the load circuit LD is -0.1 dB. That is, the power transmission efficiency was 98%. 97 kHz is the first resonance frequency f.

  The graph of FIG. 17 shows a graph comparing the current flowing through the local relay coil LM with the power receiving coil LU approached and the current Imo flowing through the local relay coil LM when the power receiving coil LU is not present. This graph is a graph in which the current value of the local relay coil LM in each case is relatively compared when the frequency of the AC power of the power supply circuit SC is changed from 60 kHz to 110 kHz.

  In the graph of FIG. 17, the current values are compared at the first resonance frequency f where the frequency of the AC power supplied from the power supply circuit SC is 97 kHz. When the current Imo that flows through the local relay coil LM when the power receiving coil LU does not exist is compared with the current that flows through the local relay coil LM when the power receiving coil LU approaches the local relay coil LM, the local relay when the power receiving coil LU approaches The value of the current flowing through the coil LM increases. That is, when the power receiving coil LU approaches the local relay coil LM, a switching function that increases the current value of the first resonance frequency f flowing through the local relay coil LM appears.

  Accordingly, when the power receiving coil LU does not approach the local relay coil LM, the current flowing through the local relay coil LM is small, and in this case, unnecessary radiation due to the current generated by the local relay coil LM is reduced.

  In addition, this invention is not limited to the above embodiment, Each coil of this invention is not limited to 1 winding coil, A coil with a large inductance can be used by a multiple winding coil. In this case, a small capacity that is in inverse proportion to the inductance of the coil is sufficient as the capacity for resonance that maintains the resonance frequency of the resonance circuit at a predetermined design value.

  Further, the present invention provides a plurality of local relay coils LM arranged in the vertical and horizontal directions so as to fill the planar area, and is locally relayed to the power receiving coil LU facing the local relay coil LM at any position in the planar area. A wireless power transmission system that supplies power from the coil LM can also be configured.

  The present invention can also be configured as a wireless power transmission system having a circuit configuration in which the power supply circuit SC and the load circuit LD in the circuit of the above embodiment are replaced.

  In the present invention, AC power having the first resonance frequency f is supplied from the power supply circuit SC to the parallel power supply unit 3. The power parallel feeding means 3 feeds the AC power of the frequency f to the local relay coil LM. Then, a resonance current of the first resonance frequency f is induced in the local relay coil LM that is close to the power receiving coil LU, so that the local relay coil LM is connected to a relay path that transmits wireless power to the power receiving coil resonance circuit 1. Become. In other words, the local relay coil LM is a wireless power transmission system that functions as a switch in which ON / OFF of relaying of AC power is controlled depending on whether or not the power receiving coil LU is approaching.

  INDUSTRIAL APPLICABILITY The present invention can be applied to non-contact power feeding to an electric vehicle and applications in which inductive power is fed to an electronic device installed on a desk via a desk plate. Further, the present invention can be applied to an application in which AC power or AC electric signal is transmitted in a non-contact manner between wiring layers of an integrated circuit within a semiconductor integrated circuit.

DESCRIPTION OF SYMBOLS 1 ... Receiving coil resonance circuit 2 ... Local relay resonance circuit 3 ... Parallel electric power feeding means A ... Arrangement position A of receiving coil LU
B: Arrangement position B of receiving coil LU
Cc1, Cc2, Cc3, Cc4, Cc5, Cc6 ... Coupling capacitors CM, CM1, CM2, CM3, CM4, CM5, CM6 ... Local resonance capacitors CP1, CP2, CP3, CP4, CP5, CP6 ... Coupling capacitor CU: Receiving resonance capacitor CW: Shared capacitor f: Frequency of AC power of power supply circuit h: Height Imo of receiving coil LU above local relay coil LM: Receiving coil Current LA flowing in the local relay coil when there is no current feed line pair LA1, LA2 ... feed lines Lc1, Lc2, Lc3, Lc4, Lc5, Lc6 ... coupling inductance LD ... load circuit LM, LM1, LM2, LM3, LM4, LM5, LM6 ... Local relay coils LP, LP1, LP2, LP3, LP4, LP5, LP6 ... Power feeding Input impedance SC · · · power supply circuit of the output impedance R2 · · · load circuit of the relay coil LU · · · receiving coil LW · · · shared inductance R1 · · · power supply circuit

Claims (5)

  A power reception coil resonance circuit configured by connecting a power reception resonance capacitor to a power reception coil and connecting a load circuit; a local relay resonance circuit configured by connecting a local resonance capacitor to a local relay coil; A power parallel feeding means for supplying AC power to the relay resonance circuit, and the first resonance frequency of the local relay resonance circuit and the power reception coil resonance circuit when the power reception coil approaches the local relay coil, Different from the second resonance frequency of the local relay resonance circuit when the power receiving coil is not approaching the local relay coil, the AC power of the first resonance frequency is fed from the power parallel feeding means, The wireless power transmission system according to claim 1, wherein the local relay coil approaching the power receiving coil is used as a relay path for transmitting the AC power to the power receiving coil.   The wireless power transmission system according to claim 1, wherein the parallel power feeding unit includes a power feeding relay coil that is inductively coupled to the local relay coil.   2. The wireless power transmission system according to claim 1, wherein the parallel power feeding means has an electrode terminal connected to the local relay resonance circuit, and a coupling capacitor is inserted in series with the electrode terminal. Wireless power transmission system.   2. The wireless power transmission system according to claim 1, wherein the parallel power feeding means has an electrode terminal connected to the local relay resonance circuit, and a coupling inductance is inserted in series with the electrode terminal. Wireless power transmission system.   2. The wireless power transmission system according to claim 1, wherein the parallel power feeding unit includes an electrode terminal connected to the local relay resonance circuit, and a parallel circuit of a coupling capacitance and a coupling inductance is connected in series to the electrode terminal. A wireless power transmission system, wherein the wireless power transmission system is inserted.

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