KR101715269B1 - Omnidirectional resonator in x-y plane using a crisscross structure for wireless power transfer, wireless power transfer apparatus and wireless power transfer system including the resonator - Google Patents

Abstract

A resonator for wireless power transmission includes: a pillar-shaped resonator; and a resonance coil which is connected to a power source, penetrates a lower part, a side, and an upper part of the resonator, penetrates the side of the resonator at least four times so as to be parallel to the center line of the pillar-shaped resonator, and has a cross-shaped structure which does not intersect when viewed from the upper part of the resonator and the lower part of the resonator. Accordingly, the present invention can constantly maintain output in a two-dimensional direction, thereby increasing the transmission efficiency of wireless power power transmission and the degree of freedom of a receiver.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resonator for radiating power in all directions in an xy plane using a cruciform structure, a radio power transmission device including the resonator, and a radio power transmission system including the same. BACKGROUND ART WIRELESS POWER TRANSFER SYSTEM INCLUDING THE RESONATOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless power transmission resonator radiating in all directions in an xy plane using a cross structure, a wireless power transmission apparatus including the resonator, and a wireless power transmission system including the same. More particularly, And is applied to a wireless power transmission capable of achieving efficiency.

Wireless power transmission or wireless energy transfer, which transfers electric energy to a desired device wirelessly, has already begun to be used in electric motors and transformers using electromagnetic induction in the 1800s, Frequency) or by emitting a laser to transfer electrical energy.

Our electric toothbrushes and some wireless shavers are actually charged with electromagnetic induction. Up to the present, the energy transmission method by the radio system includes magnetic induction, self resonance, and a remote transmission technique using a microwave.

In recent years, among such wireless power transmission techniques, energy transmission using self resonance is widely used. In the wireless power transmission system using self-resonance, since the electric signals formed on the transmission side and the reception side are wirelessly transmitted through the coil, the user can easily charge electronic devices such as portable devices.

On the other hand, modern growth industries are various fusion industries based on ICT. In particular, the development of information and communication technology is rapidly developing toward improving the freedom of users in addition to mobile communication technology. In recent years, there has been a proliferation of mobile communication technologies such as smart phones, DMB, and tablet PCs, which show rapid increase in demand, as well as products with a focus on user mobility.

In the application of wireless power transmission of a general magnetic resonance method, the transmission coil and the reception coil must face each other to obtain effective transmission efficiency. 1 shows a transmission coil and a reception coil when the transmission coil resonator has a single plane structure. Tx is an abbreviation of Transmitter, which represents a transmitter, that is, a transmission coil, and Rx stands for a receiver, which represents a receiver, that is, a receiver coil. and? represents the angle at which the receiving coil is inclined with respect to the x-y plane.

1, the mutual inductance between the transmitting coil and the receiving coil changes abruptly. Therefore, in the single plane structure, mutual inductance is changed according to the movement of the receiving coil when the coil is a transmission coil, and the power transmission efficiency is determined. That is, it can be seen that as the angle between the receiver and the transmitter becomes closer to the vertical, the power transmission efficiency decreases drastically. For example, the transmission efficiency is determined by the mutual inductance. When? Is 0, the mutual inductance is strong and the transmission efficiency is high. However, when? Is 180, mutual inductance is low and the transmission efficiency is low.

This causes a problem of reducing the degree of freedom of the wireless power transmission receiver. Therefore, omni-directional wireless power transmission is required to improve the degree of freedom of the receiver, which is the most important problem in wireless power transmission.

KR 10-2014-0129930 A KR 10-2014-0031518 A

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a radio power transmission resonator radiating in all directions in an xy plane using a cross structure, .

Another object of the present invention is to provide a wireless power transmission apparatus including the resonator.

It is still another object of the present invention to provide a wireless power transmission system including the resonator.

According to an aspect of the present invention, there is provided a resonator for a wireless power transmission including: a columnar resonator; And a power source connected to the resonator through a lower surface, a side surface, and an upper surface of the resonator, wherein a side surface of the resonator is passed through at least four times so as to be parallel to a center line of the columnar resonator, A resonant coil with a cross-shaped structure that does not intersect when viewed from the underside of the sieve

In an embodiment of the present invention, the resonance coil passes through the lower surface, the side surface, and the upper surface of the resonator, passes through the upper surface, the side surface, and the lower surface, passes through the lower surface, the side surface, , The upper surface, the side surface, and the lower surface.

In an embodiment of the present invention, the resonant coil may pass the closed loop more than once.

In the embodiment of the present invention, the resonator may have a prism shape.

In an embodiment of the present invention, the resonator may have a cylindrical shape.

In an embodiment of the present invention, the resonator may have a shape in which two plates are orthogonal to the center line.

In an embodiment of the present invention, the resonator may be hollow.

In an embodiment of the present invention, the resonator may be formed of a dielectric.

In an embodiment of the present invention, the resonator may be formed of acrylic or glass.

According to another aspect of the present invention, there is provided a wireless power transmission apparatus including: a columnar resonator; A power source for supplying power; And a power source connected to the resonator through a lower surface, a side surface, and an upper surface of the resonator, wherein a side surface of the resonator is passed through at least four times so as to be parallel to a center line of the columnar resonator, And a resonant coil having a cross-shaped structure that does not intersect when viewed from the bottom of the sieve.

In the embodiment of the present invention, the resonator may have a cylindrical shape or a prism shape.

In an embodiment of the present invention, the resonator may be hollow.

According to another aspect of the present invention, there is provided a wireless power transmission system including: a columnar resonator; A power source for supplying power; And the resonator is connected to a power source and passes through a lower surface, a side surface, and an upper surface of the resonator, and passes through the side surface of the resonator at least four times so as to be parallel to the center line of the columnar resonator, A resonance coil having a cross-shaped structure that does not intersect when viewed from the lower side of the resonator; And a receiving resonant coil coupled to the transmitting resonant coil to receive power.

In the embodiment of the present invention, the resonator may have a cylindrical shape or a prism shape.

In an embodiment of the present invention, the receiving resonant coil may be formed inside the load terminal.

According to such a wireless power transmission resonator, the transmitter is formed in a cross structure, and the magnetic field is changed by half a period to radiate uniformly in all directions in the x-y plane, thereby enabling wireless charging in any direction. Accordingly, a uniform transmission efficiency can be obtained at the same distance, and the transmission efficiency can be controlled by changing the number of times the resonance coil is wound. Further, since the degree of freedom of the receiver is increased, the present invention can be applied to terminals of various shapes and shapes.

1 is a diagram illustrating a conventional wireless power transmission system.
2 is a circuit diagram of a wireless power transmission unit of a resonance type.
3 is a conceptual view of a resonant coil of a resonator for wireless power transmission according to the present invention.
4 is a wireless power transmission resonator according to an embodiment of the present invention.
5 is a plan view showing a coiled shape of the resonance coil on the upper surface of the resonator for wireless power transmission of FIG.
6 to 8 are examples of resonators for wireless power transmission according to other embodiments of the present invention.
9 and 11 are views showing a magnetic field vector induced in accordance with a current flow in the resonator for wireless power transmission according to the present invention.
FIGS. 12 and 13 are diagrams for simulating a magnetic field vector for half a period in the resonator for wireless power transmission of the present invention. FIG.
14 is a diagram illustrating an example of a wireless power transmission system according to an embodiment of the present invention.
15 and 16 are graphs showing the transmission efficiency according to a distance change of the resonator for a wireless power transmission and the receiver of the present invention.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

Due to the convenience of wireless power transmission, research on wireless power transmission has been actively conducted worldwide. Generally, the mutual inductance changes abruptly according to the change of the reception coil angle with respect to the transmission coil. That is, the transmission efficiency varies depending on the angle. However, since changes in angle in real life are obvious, wireless power transmission in all directions is necessary.

In the present invention, a resonator that can generate resonance in two dimensions in all directions is proposed by designing a cross structure to make the output constant.

Resonance refers to a phenomenon in which an object having a specific frequency increases in amplitude while the same frequency is externally applied, and a strong force is generated when the frequency is equal. Therefore, two resonators having the same frequency have very strong coupling.

That is, if there is another resonant object with the same frequency, the energy is transmitted strongly from one object sharing frequency to another. All objects have these natural frequencies and have the property of reacting and absorbing the waves or waves corresponding to this natural frequency.

2, there is shown an equivalent circuit of a resonant type wireless power transmission system. Each element is defined as shown in Table 1 below.

device characteristic V AC Voltage Source R _l Ohmic Resistance of the Loop R _r Radiation Resistance of the Loop C Capacitance of the Resonance M Mutual Inductance between Resonators I Current Flowing on the Loop L Self-Inductance of the Loop

The transmission efficiency, which is the performance of a resonant-based wireless power transmission system, is affected by the coupling factor (k) and resonant Q-factor characteristics between the two resonators. Equation 1 below represents the minimum loss of the magnetic resonance wireless power transmission system.

In the case of a magnetic-field-resonant wireless power transmission system, resonance Q-factor characteristics are improved if two transmit and receive coils spaced apart at a certain distance resonate at the same frequency. However, since the two transmission and reception coils are spaced apart from each other, the coupling coefficient between the transmission and reception resonators decreases sharply as the transmission distance increases.

That is, the coupling coefficient reduction between the transmitting and receiving resonators occurring when the distance between the two transmitting and receiving resonators is distant can be compensated by the improved resonant Q-factor characteristic generated when the two transmitting and receiving resonators resonate at the same frequency.

Therefore, in the case of the magnetic induction type wireless power transmission, when the distance between the transmitting and receiving coils becomes long, the coupling coefficient sharply decreases and the transmission efficiency also sharply decreases. However, in the case of magnetic resonance wireless power transmission, coupling coefficient can be compensated through improved coupling coefficient and improved resonance Q-factor characteristics. Therefore, higher transmission efficiency is designed at a longer transmission distance than that of the magnetic induction type wireless power transmission .

This can be confirmed from the equation (1). If the value of k decreases, the loss value becomes larger. However, if the Q-factor value increases at the same time, the loss value is maintained or decreased. That is, the higher the Q-factor value, the higher the energy transfer efficiency. Ideally, the Q value has a value of 0 to infinity, but it generally involves technological difficulties to have a value of 1000 or more. In addition, the resonance Q value shows the greatest change according to the size of the antenna, and changes depending on the shape, material, and operating frequency. The following equation (2) represents the Q-factor of the resonator.

In the application of wireless power transmission of a general magnetic resonance method, the transmission coil and the reception coil must face each other to obtain effective transmission efficiency. Referring to FIG. 1, a conventional transmission coil and a reception coil in which a transmission coil resonator has a single plane structure are shown. Tx is an abbreviation of Transmitter, which represents a transmitter, that is, a transmission coil, and Rx stands for a receiver, which represents a receiver, that is, a receiver coil. and? represents the angle at which the receiving coils are inclined with respect to the x-y plane.

It can be seen that, when the angle &thetas; of the receiving coil is changed with respect to the system of FIG. 1, the mutual inductance between the transmitting coil and the receiving coil is drastically reduced. Therefore, in the single plane structure, mutual inductance is changed according to the movement of the receiving coil when the coil is a transmission coil, and the power transmission efficiency is determined. That is, it can be seen that as the angle between the receiver and the transmitter becomes closer to the vertical, the power transmission efficiency decreases drastically.

A dead zone is generated in which the mutual inductance becomes zero according to the position and arrangement of the receiving coil with respect to the transmitting coil in the planar self-resonant wireless power transmission. In the dead zone, no power is transferred from the transmit coil to the receive coil. This causes a large problem in the degree of freedom of the wireless power transmission receiver.

Therefore, there is a need for an omnidirectional wireless power transmission unit to improve the degree of freedom of the receiver, which is the most important problem in wireless power transmission.

To this end, a resonator for a wireless power transmission according to the present invention is designed with a cross structure, and outputs it in two-dimensional all directions using it, and it is tried to overcome the limit by applying it to a wireless power transmission. In the x-y plane wireless power transmission according to the present invention, the dead zone is reduced so that the power can be transmitted regardless of the position of the receiving coil.

3 and 4, the resonance coil 20 of the resonator for radio power transmission 1 (hereinafter, referred to as a transmission resonator) according to an embodiment of the present invention includes a resonance coil 20, which does not intersect the plan view viewed from above and the plan view seen from below It has a cross-shaped structure.

The transmission resonator 1 includes a resonance coil 20 connected to the columnar resonator 10 and the power source 30 and radiating the resonance two-dimensionally in all directions. The resonance coil 20 is composed of a single coil, and both ends are connected to the power source 30. However, it may include a power supply coil which is formed separately from the resonance coil 20 by a predetermined distance.

 The resonance coil 20 passes through the lower surface, the side surface, and the upper surface of the resonator 10 at least four times so as to be parallel to the center line of the columnar resonator 10.

The resonator 10 may have a prismatic shape or a cylindrical shape. In the embodiment of Fig. 4, the resonator 10 has an octagonal columnar shape.

The octagonal columnar resonator 10 has a top surface 100 and a bottom surface 300 of octagonal shape and eight rectangular side surfaces 201 to 208. In this case, when the resonance coil 20 passes through the first surface 201, a third surface 201, which is an internal angle perpendicular to the first surface 201 with respect to the center point 0 of the top surface 100, A fifth surface 205 facing the first surface 201 and a seventh surface 207 forming an inner angle perpendicular to the fifth surface 205 with respect to the center point.

When passing through the side surfaces, the resonance coil 20 can pass through the center of each side surface parallel to the center line of the resonator 10, and do not overlap or cross each other.

Referring to FIG. 5, in the upper surface 100, the resonance coil 20 has a cross shape and does not overlap or cross each other. It is as if the four "a" shapes meet the vertices. Although not shown, the shape of the resonance coil 20 of the lower surface 300 is also the same.

The resonance coil 20 forms a closed loop and can pass the same closed loop more than once. However, since the resonance coils 20 do not overlap or cross each other, they may have a spiral structure. 4, the resonance coil 20 is wound five times.

However, the manner in which the resonance coil 20 is wound is merely an example, and it is possible to pass the required number of times in a necessary manner in a condition having a cross-shaped plane that does not intersect. The resonance coil 20 can pass through all or some of the surfaces of the resonator 10, and the number of times of passage of the resonator 20 can be the same.

The resonator 10 may be hollow and may be formed of a dielectric material. For example, the resonator 10 may be formed of acrylic or glass.

The resonator 10 may have a prismatic shape or a columnar shape as described above, and may have any other structure capable of winding the resonator 10 in a cross structure that does not cross the resonance coil 20.

6, the resonator 12 has a square pillar shape, and the resonance coil 22 passes all the side faces of the rectangular pillar-shaped resonator 12 by the same number .

Referring to FIG. 7, as another embodiment of the present invention, the resonator 13 has a shape in which two plates are orthogonal to the center line, and the resonant coil 23 passes through the side surfaces of the plates.

8, the resonator 14 has a cylindrical shape, and the resonance coil 24 has two identical pairs of opposing side faces on the side face of the cylindrical resonator 14 .

The shapes of the resonators shown in Figs. 6 to 8 are merely examples, and they can be transformed into any shape under the condition that the resonance coil can be wound in a cross shape.

When the resonance coil 20 has a cross shape, when a power is applied to the resonance coil 20, a magnetic field is formed in a two-dimensional all-direction direction, thereby enabling wireless power transmission in a two-dimensional forward direction.

For example, the size of the transmission resonator 1 is 200 x 200 x 200 mm in width × height × height, and a Litz wire having a diameter of 1 mm is used. The coil inductance of the transmission resonator 1 is 22.07 μH and the Q value is 77.51. Through this, LC resonance was applied. The reflection characteristic S11 was -29.7 dB at a resonance frequency of 6.63 MHz. A simulation was conducted to confirm the magnetic field distribution by applying electric power.

9 to 11 are diagrams showing the distribution of the magnetic field vectors in the respective planes of the transmission resonator 1 according to the power input.

Referring to FIG. 9, a current vector and a magnetic field vector for a half period of 0 to? Are shown, and a magnetic field is formed inside and outside the transmission resonator 1 with an electric current flowing. x, + y, and -y axes, and the inner magnetic field vectors combine with each other and radiate in oblique directions at 45 ° and 225 ° in the xy plane.

Referring to FIG. 10, a current vector and a magnetic field vector for a half period of? 2? Are shown. A current is generated and a magnetic field is formed inside and outside the transmission resonator 1, x, + y, and -y axes, and the internal magnetic field vectors combine with each other and radiate in diagonal directions of 135 ° and 315 ° in the xy plane.

11, the sum of the vector of the internal magnetic fields of the transmitting resonator 1 is generated in the xy-plane diagonal line for one period, and + x, -x, + y, and -y due to the external magnetic field vector of the transmitting resonator 1 Since it emits radiation, it radiates in all directions in two-dimensional xy plane. As a result, wireless power transmission is possible in the two-dimensional x-y plane forward direction

FIGS. 12 and 13 are diagrams for simulating a magnetic field vector for half a period in the resonator for wireless power transmission of the present invention. FIG.

Referring to FIG. 12, a simulation result of a magnetic field vector generation during a half period of 0 to? Is shown. Referring to FIG. 13, as a simulation result of a magnetic field vector generation during a half period of? As shown in FIG.

FIG. 14 is a block diagram of a wireless power transmission system according to an embodiment of the present invention, which includes a transmission resonator 1 including a columnar resonator 10 and a transmission resonant coil 20, And a receiver 7 including a wireless power transmission device including a power source 30 for receiving the power and a receiving resonant coil 72 coupled to the transmitting resonant coil 20 to receive power. In an actual implementation, the receiver 7 may be formed within the device to be charged or the terminal.

The receiver 7, which receives power from the wireless power transmission apparatus, may have various shapes. For example, the receiving resonance coil 72 using a Litz wire having a diameter of 1 mm was formed in a single plate 71 having a width × length × height of 200 × 200 × 15 mm and having a 15-turn helical structure. At this time, the resonance frequency is 6.78 MHz.

The transmission resonator 1 is formed in a size of 200 x 200 x 200 mm in width × height × height and 5 turns of a Litz wire of 1 mm in the embodiment of FIG. 4 as the transmission resonator 1 and the receiver 7) is 200 mm.

In the logarithmic scale, S11 is -24.431 dB and S22 is -32.079 dB. At this time, the Q value of the transmission resonator 1 is 49.17 and the Q value of the receiver 7 is 78.42. Table 2 below shows the transmission efficiency according to the change in angle between the transmission resonator 1 and the receiver 7. [

Angle of transmit resonator and receiver 0 ° 45 ° 90 ° 135 ° 180 ° 225 ° 270 DEG 315 ° S ₂₁ (dB) -2.96 -2.65 -2.83 -2.66 -3.12 -2.62 -3.05 -2.65 Transmission efficiency (%) 50.58 54.33 52.12 54.2 48.75 54.7 49.55 54.33

The transmission efficiency was measured by giving an angle change from 0 ° to 315 ° at intervals of 45 °. As a result, it was 48.75 to 54.7%, which is 50% uniform in all directions. The transmission efficiency is better than the + x, -x, + y, and -y axes because of the emission of diagonal lines due to the coupling of the internal magnetic field.

15 and 16 show the transmission efficiency measured in the transmission resonator 1 implemented according to the present invention.

Referring to FIG. 15, the transmission efficiency according to the change in distance between the transmission resonator 1 and the receiver 7 when the transmission resonator 1 and the receiver 7 face each other is shown in FIG. 14, The transmission efficiency is shown by the distance change when the transmission resonator 1 is rotated by 45 degrees.

X, -x, + y, and -y axes (0 °, 90 °, 180 °) because the oblique directions (45 °, 135 °, 225 °, 315 °) occur due to the sum of the internal magnetic field vectors of the transmission resonator °, 270 °), respectively. Therefore, the transmission efficiency according to the distance variation was confirmed by dividing by 0 ° and 45 °. It is because of overcoupling that the spill-tick phenomenon occurs as the distance between the transmission resonator 1 and the receiver 7 approaches.

The transmission resonator according to the present invention has a radiation characteristic in the x-y all directions. Specifically, by using a cross structure to change the magnetic field vector by half period, it has the omnidirectional characteristic, and the transmission efficiency can be controlled by changing the number of times the resonance coil is wound around the structure. Accordingly, uniform transmission efficiency can be obtained at the same distance as compared with the conventional resonator, and the receiver can be applied to terminals of various shapes and shapes because the degree of freedom of the receiver is increased by the omnidirectional radiation of the transmitter.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. You will understand.

The present invention is designed to reduce the dead zone occurring in wireless power transmission so that power can be transmitted regardless of the position of the receiving coil. Accordingly, it is expected to contribute to the activity of the wireless charging market by solving the problem of lowering the degree of freedom of the receiver, which is a general wireless charging method.

1: transmitting resonator
10, 12, 13, 14: Resonator
20, 22, 23, 24: resonant coil
30, 32, 33, 34: power source

Claims (15)

A columnar resonator; And
And the resonator is connected to a power source and passes through a lower surface, a side surface, and an upper surface of the resonator, and passes through the side surface of the resonator at least four times so as to be parallel to the center line of the columnar resonator, Wherein the resonator has a cross-shaped structure that does not intersect when viewed from the bottom of the resonator.
The method according to claim 1,
The resonance coil passes through the lower surface, the side surface, and the upper surface of the resonator, passes through the upper surface, the side surface, and the lower surface, passes through the lower surface, the side surface, and the upper surface, Wherein the resonator is a closed loop via the lower surface.
3. The method of claim 2,
Wherein said resonant coil passes said closed loop more than once.
The method according to claim 1,
Wherein the resonator is a prismatic shape.
The method according to claim 1,
Wherein the resonator is a columnar resonator.
The method according to claim 1,
Wherein the resonator has a shape in which two plates are orthogonal to the center line.
The method according to claim 1,
Wherein the resonator is hollow.
The method according to claim 1,
Wherein the resonator is formed of a dielectric.
9. The method of claim 8,
Wherein the resonator is formed of acrylic or glass.
A columnar resonator;
A power source for supplying power; And
And the resonator is connected to a power source and passes through a lower surface, a side surface, and an upper surface of the resonator, and passes through the side surface of the resonator at least four times so as to be parallel to the center line of the columnar resonator, Wherein the resonant coil has a cross-shaped structure that does not intersect when viewed from the bottom side of the resonant coil.
11. The method of claim 10,
Wherein the resonator is a columnar or prismatic shape.
11. The method of claim 10,
Wherein the resonator is hollow.
A columnar resonator;
A power source for supplying power;
And the resonator is connected to a power source and passes through a lower surface, a side surface, and an upper surface of the resonator, and passes through the side surface of the resonator at least four times so as to be parallel to the center line of the columnar resonator, A transmission resonance coil having a cross-shaped structure that does not intersect when viewed from the bottom side of the transmission resonance coil; And
And a receiving resonant coil coupled to the transmitting resonant coil to receive power.
14. The method of claim 13,
Wherein the resonator is cylindrical or prismatic.
14. The method of claim 13,
Wherein the receive resonant coil is formed inside the load terminal.

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