WO2014109460A1 - Wireless power transmission system for free-position wireless charging of multiple devices - Google Patents

Abstract

The present invention relates to a near-field wireless power transmission system capable of having a constant efficiency regardless of a charging position of a receiver by only using a simple impedance matching circuit without using a separate existing complex adaptive impedance matching circuit or control circuit, and simultaneously transmitting power without having difficulty with impedance matching even for wireless power transmission to a plurality of electronic devices by applying a structure having a uniform mutual inductance between a wireless power transmitter and receiver.

Description

Wireless power transmission system for free location wireless charging of multiple devices

The present invention relates to a short range wireless power transfer system, and more particularly, to a short range wireless power transfer system using a structure having a uniform mutual inductance between wireless power transceivers.

1 is an equivalent circuit of a general electromagnetic induction type wireless power transmission system using each resonant coil of a transceiver. The magnetic inductance L ₁ of the transmitting coil (Tx coil), the resistance is R ₁ , the capacitance for resonance is C ₁ , the magnetic inductance L ₂ of the receiving coil (Rx coil), the resistance is R ₂ , and the capacitance for resonance is When C ₂ , the power of the transmitting coil (Tx coil) receiving the AC source signal (Vs) is transferred to the load (impedance Z _L ) connected to the receiving coil (Rx coil) according to the magnetic field coupling according to mutual inductance M ₁₂ . Can be. The power transmission unit including a transmission coil (Tx coil) is provided in a transmitter device for power transmission, and the power reception unit including a reception coil (Rx coil) is provided in various electronic devices that use electric power such as a smartphone and an iPad. The electronic device may be positioned close to the power supply to wirelessly supply power to the load (eg, a battery, an operation circuit, etc.) through the Rx coil of the electronic device.

However, in such a wireless power transmission system, the strength of the magnetic field coupling between the transmission and reception coils (Tx coil, Rx coil) as described above depends on the transmission and reception coil structure, geometric arrangement and position, the distance between the transmission and reception coils. As the magnetic field coupling strength between the transmitting and receiving coils changes according to various environmental changes, the optimal power transfer condition of the wireless power transmission system is changed, so that an additional impedance matching circuit or an optimal impedance matching circuit is provided on the transmitter or receiver side to satisfy the maximum power transfer condition. In order to control the power delivery condition, complexity such as a current voltage sensing circuit is required. In particular, when a flat panel transmitter is used, it is difficult to support wireless power transmission at a free position between the transmitter and the receiver because an optimum impedance must be matched according to the position of the receiver placed on the flat panel. . In addition, if the mutual inductance between the transmitting and receiving coils are different for each position, or if the multiple devices are located at different positions to receive power, the transmitter may have difficulty in matching impedances to the individual devices, and thus it may not support power transmission to the multiple devices at the same time. There is this.

Regarding the conventional wireless power transfer technology for maximum power transfer between the transceivers, various documents exist, but the following four documents are introduced.

(1) A. Kurs, A. Karalis, R. Moffatt, J. D. Joannopoulos, P. Fisher, and M. Soljacic, "Wireless power transfer via strongly coupled magnetic resonances", Science, vol. 317, pp. 83-86, July 2007.

(2) J. Park, Y. Tak, Y. Kim, Y. Kim, S. Nam, "Investigation of adaptive matching methods for near-field wireless power transfer", IEEE Transactions on Antennas and Propagation, vol. 59, pp. 1769-1773, May 2011.

(3) W.S. Lee, H.L. Lee, K.S. Oh, and J.W. Yu, "Uniform magnetic field distribution of a spatially structured resonant coil for wireless power transfer" Applied physics Letters 100, 2012.

(4) W. S. Lee, W. I. Son, K. S. Oh, and J. W. Yu, "Contactless energy transfer systems using antiparallel resonant loops" IEEE transactions on industrial electronics, Vol. 60, no. 1, January 2013.

In the above document (1), in addition to the transmission and reception resonant coil, the transmission and reception coupling coil is used to satisfy the maximum power transfer condition that varies according to the change in distance, but this method requires limited physical movement of the additional transmission and reception coupling coil. In case of using, there is a problem that is difficult to apply.

In the above document (2), a method of tracking an optimum frequency for maximum power transmission according to the distance of a transmission / reception resonance coil is disclosed. However, when the frequency for short range wireless power transmission is fixed, it is difficult to use such a frequency tracking method.

The above document (3) proposed a structure that has a uniform magnetic field distribution at a certain height of the coil by bending the shape of the square coil, but this structure has a disadvantage in that the shape of the coil must be changed mechanically. In addition, if the receiver does not have a uniform magnetic field, there is a disadvantage in that it does not have a uniform mutual inductance or a uniform figure of merit.

The above document (4) discloses a method of maintaining mutual inductance that varies with the distance of a transmission / reception coil using two loop coils connected in series in which the current direction operates in reverse. This is only possible when the center axes of the transmit and receive coils are coincident, but free positioning of the receiver on a flat panel transmitter is difficult and wireless charging of a plurality of receiving devices placed on the transmitter is difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a structure having a uniform figure of merit (FoM), that is, a uniform mutual inductance between wireless power transceivers. It is possible to have a constant efficiency regardless of the charging position of the receiver by using only a simple impedance matching circuit without using a complicated adaptive impedance matching circuit or a control circuit separately. The present invention provides a short range wireless power transmission system capable of simultaneously transmitting power without difficulty.

First, to summarize the features of the present invention, according to one aspect of the present invention, the coil structure for wireless power transmission, the current flowing in the direction of the input current applied from one end, from one end to the other end, the nose A coil portion connected to and partially concentric with the coil portion in which the current flows in the direction of the input current, the coil portion flowing in a direction opposite to the input current, and having a relative center position horizontally with each target coil. It is for wireless power transfer according to mutual inductance.

The target coil may be one coil having a relatively horizontal center of position change, or a plurality of coils having a relatively different horizontal center position.

For each target coil, the coil structure may have a uniform mutual inductance in a predetermined range.

The magnetic field at the center of the coil structure may be increased relatively to have uniformity of mutual inductance with other coils.

Coils constituting the coil structure may be formed using a printed circuit board process or a semiconductor process, and coils formed by being distributed and disposed in a multilayer may be connected through a via hole.

Each coil part of the coil structure may have a shape wound in a concentric circle or a concentric polygon.

The coil part in which current flows in the direction of the input current may include a coil part wound to be concentric in the center direction a plurality of times so that the current flows in the direction of the input current.

The coil unit in which current in a direction opposite to the input current flows may include a coil unit wound in parallel with two or more strands so that a current in a direction opposite to the input current flows.

The coil unit wound by connecting two or more strands in parallel may be wound single or multiple times.

In addition, the coil structure according to another aspect of the present invention, between one end and the other end, including a coil portion flowing current in the direction of the input current applied from the one end, the current in the direction of the input current The first coil part wound to be concentric in the center direction in a single or multiple times to flow with the center, and the second coil part wound to be concentric in two or more strands connected in parallel so that a current flows in the direction of the input current. It includes, and is for the wireless power transfer according to the mutual inductance with each target coil horizontally different relative center position.

The second coil part wound to form two or more concentric lines connected in parallel may be wound single or multiple times.

The coil structure may further include a third coil part wound so as to be concentric with two or more strands connected in parallel so that a current in a direction opposite to the input current flows.

The second coil portion may be disposed at the center or the outermost portion.

In addition, according to another aspect of the present invention, in the wireless power transmission system for transmitting and receiving power between the transmitter coil and the receiver coil of the receiver by magnetic coupling, the transmitting coil or the receiving coil, one side A first coil part wound from the end to the other end so as to be concentric in the center direction of the single or multiple times so that the current flows in the direction of the input current applied from the one end; And a coil part connected to the first coil part in which current flows in the direction of the input current, the center of the first coil part being coincident with the center and being concentric, and in which a current in a direction opposite to the input current flows, or the center is coincident with the first coil part. And a coil unit wound in parallel to be concentric with two or more strands connected in parallel so that current flows in the direction of the input current, and transmits power to each of the one or more receiving coils whose center positions are horizontally different from each other in the transmitting coil. It is characterized by.

For each of the receiving coils, it is possible to have a uniform mutual inductance in a predetermined range between the transmitting coils.

The uniform mutual inductance may be used to transmit power without changing impedance matching at the transmitter or the receiver.

The transmitter may comprise means for impedance matching of the transmitting coil between an alternating source signal Vs and the transmitting coil.

The transmitter includes a source coil connected to an AC source signal that is a voltage source, a current source, or a power source, and coupled to a magnetic field spaced apart from a direct connection to the transmitting coil, by mutual inductance between the source coil and the transmitting coil. Impedance matching can be made.

A capacitor may be included between one end of the AC source signal and one end of the source coil.

The transmitter may include a transformer for impedance matching, the primary side of which is connected to an AC source signal which is a voltage source, a current source, or a power source, and the secondary side of the transmitting coil.

The transmitter may include a capacitor for impedance matching connected between the AC source signal, which is a voltage source, a current source, or a power source, and the transmitting coil.

The transmitter may include an inductor for impedance matching connected between the AC source signal, which is a voltage source, a current source, or a power source, and the transmitting coil.

The receiver may comprise means for impedance matching to the load between the receiving coil and the load.

The receiver may include a load coil connected to a load and coupled to a magnetic field spaced apart from a direct connection with the receiving coil, and impedance matching may be performed by mutual inductance between the receiving coil and the load coil.

A capacitor may be included between one end of the load coil and one end of the load.

The receiver may include a transformer for impedance matching, in which the receiving coil and the primary side are connected and the load and the secondary side are connected.

A capacitor may be included between one end of the secondary side and one end of the load.

The receiver may include an inductor for impedance matching connected between a load and the receiving coil.

The receiver may include a capacitor for impedance matching connected between a load and the receiving coil.

A capacitor may be further included between one end of the inductor and one end of the load.

The transmitter includes a sensing circuit for sensing a load variation according to the quantity of the receiving coils, and by controlling the means for impedance matching to adjust the input impedance changed according to the load variation through the sensing circuit impedance matching is performed; Can be done.

In addition, according to another aspect of the present invention, a wireless power transmission method includes transmitting power wirelessly using an AC source signal in a transmission coil; And wirelessly receiving the power in a receiving coil spaced apart from the transmitting coil by magnetic coupling, wherein the transmitting coil or the receiving coil is between one end and the other end. A first coil part wound to be concentric in the center direction of the single or multiple times so that the current flows in the direction of the input current applied from the; And a coil part connected to the first coil part through which current flows in the direction of the input current, the center of the coil being coincident with the center of the first coil part, and having a current flowing in a direction opposite to the input current, or the center of the coil part. And a coil unit wound in parallel so that two or more strands are connected in parallel so that a current flows in the direction of the input current, and in the step of transmitting power wirelessly, a relative center position of the transmitting coil is horizontally It is characterized in that for transmitting power to each other one or more receiving coils.

According to the short-range wireless power transmission system according to the present invention, since the adaptive impedance matching circuit does not need to be used in accordance with the change of the position between the transceiver, the complexity of the system is low and the price is low.

In addition, the use of a single coil allows free positioning of the receiver and transmitter within the wireless power transmission range or effective wireless charging range with uniform mutual inductance within 20% without additional circuitry.

In addition, since it has a constant mutual inductance within the wireless power transmission distance having a uniform mutual inductance, it is possible to simultaneously receive wireless power from a plurality of devices to provide or charge power for the operation of each device.

1 is an equivalent circuit of a general electromagnetic induction type wireless power transmission system using each resonant coil of a transceiver.

2 is a view for explaining the concept of a wireless power transmission system according to an embodiment of the present invention.

3 is a graph showing transmission and reception maximum power transmission efficiency according to a performance index (FOM) of a wireless power transmission system according to an embodiment of the present invention.

4 is an example of a calculation result for the mutual inductance (M ₁₂ ) between the transmission and reception coils in the wireless power transmission system according to an embodiment of the present invention.

5 is an example of a coil structure in accordance with one embodiment of the present invention to have an electrically uniform mutual inductance.

6 is an example of a coil actually manufactured to have the structure of FIG. 5.

7 is an example of an actual manufactured receiving coil according to an embodiment of the present invention.

8 is a result of measuring mutual inductance between transmission and reception coils of a wireless power transmission system according to an embodiment of the present invention.

FIG. 9 illustrates a configuration in which the coil structure proposed in FIG. 5 is applied to a transmitter of a wireless power transmission system according to an embodiment of the present invention.

FIG. 10 shows a detailed configuration in which the coil structure proposed in FIG. 5 is applied to a transmitter of a wireless power transmission system according to an embodiment of the present invention.

FIG. 11 shows another specific configuration in which the coil structure proposed in FIG. 5 is applied to a transmitter of a wireless power transmission system according to an embodiment of the present invention.

FIG. 12 shows another specific configuration in which the coil structure proposed in FIG. 5 is applied to a transmitter of the wireless power transmission system according to an embodiment of the present invention.

FIG. 13 shows another specific configuration in which the coil structure proposed in FIG. 5 is applied to a transmitter of a wireless power transmission system according to an embodiment of the present invention.

14 illustrates a configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

15 shows a detailed configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

16 shows another specific configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

17 shows another specific configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

18 shows another specific configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

19 shows another specific configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

FIG. 20 is an example in which the structures of FIGS. 11 and 15 are combined.

FIG. 21 is a view for explaining a magnetic field change of the proposed coil structure of FIG. 5 and the structure in which N ₃ and N ₄ are removed or N ₄ is removed from the structure of FIG. 5.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings and the contents described in the accompanying drawings, but the present invention is not limited or limited to the embodiments.

2 is a view for explaining the concept of a wireless power transmission system according to an embodiment of the present invention.

As shown in FIG. 2, a wireless power transmission system according to an embodiment of the present invention includes a transmission (resonance) coil (Tx coil) of a transmitter receiving an AC source signal Vs (magnetic inductance L ₁ , in an equivalent circuit). The resistance is R ₁ , the capacitance for resonance is C ₁ , the receiver (resonance) coil (Rx coil) of the receiver (magnetic inductance L ₂ in the equivalent circuit, the resistance R ₂ , the capacitance for resonance is C ₂ ) is provided with a matching unit (Tx matching unit, Rx matching unit) for impedance matching to the transceiver so that the maximum power can be transmitted by electromagnetic induction or magnetic field coupling according to mutual inductance M ₁₂ .

For maximum power transfer, the transmitter's Tx matching unit matches the impedance seen by the Tx coil with the input impedance Z _in (impedance seen by the source) to reflect the transmitted source signal. The Rx matching unit of the receiver for minimizing (removing) the impedance matching effect on the load (impedance Z _L ) is conjugated with the impedance seen from the Rx coil toward the load. matching) condition must be established.

At this time, if there is no conduction resistance loss by the matching unit (Tx matching unit), the maximum power transfer efficiency η (the ratio of the power delivered to the load to the transmitted power) is based on the well-known electromagnetic theory. It can be derived as shown in [Equation 1].

[Equation 1]

Here, FOM refers to the figure of merit (FoM) of the transmission and reception system. In the case of using the coil as described below in the present invention, by changing R ₁ to R _p in Equation 1, the FOM and the maximum power transfer efficiency η can be obtained. Here, f _r is the resonant frequency of the transmission / reception coil (transmission coil and reception coil), R ₁ is the resistance of the transmission coil, R ₂ is the resistance of the reception coil, and M ₁₂ is the mutual inductance of the transmission / reception coil. In Equation 1, since the resistance of the transmission / reception coil hardly changes in the position change of the transmission / reception coil, the efficiency η and the performance index FoM of the system depend on M ₁₂ .

In the present invention, the transmitter (Transmitter) can supply the wireless power with the maximum power transfer efficiency to the receiver (Receiver) as described above mounted on a variety of electronic devices using the power, such as a smart phone, iPad, wireless power transmitter (Transmitter) In a power transmission to a receiver having a fixed or mobile load (eg, battery, device operation circuit, etc.) in space, the transmitter coil (Tx coil) of the transmitter and the receiver coil (Rx) of the receiver (Receiver) The coil structure of the present invention can be applied to any one or more of the coils, and even if the adaptive impedance matching circuit is not used in accordance with the change of the position between the corresponding transceivers, it is within 20% according to the above principle as described below. Simple and inexpensive adaptation to free positioning within wireless power transmission distances with figure of merit FOM or uniform mutual inductance M ₁₂ Wireless power can be supplied with power delivery efficiency. Since there is a constant mutual inductance within the wireless power transmission distance having such a uniform mutual inductance, a plurality of devices can simultaneously receive wireless power to charge the battery or operate the device.

3 is a graph showing the maximum transmission and reception power transmission efficiency η according to the figure of merit (FOM) of the wireless power transmission system according to an embodiment of the present invention. Here, the maximum power transfer efficiency η is a case where the maximum power transfer condition is satisfied in the Tx matching unit and the Rx matching unit. As shown in FIG. 3, the efficiency η increases as the performance index FoM increases. The higher the FOM, the greater the change in maximum power transfer efficiency η according to the change in the figure of merit.

4 is an example of a calculation result for the mutual inductance (M ₁₂ ) between the transmission and reception coils in the wireless power transmission system according to an embodiment of the present invention.

As shown in (a) of FIG. 4, the transmitting coil and the receiving coil are arranged side by side so that their centers coincide with each other, and the thickness of each coil having a radius of 10 cm is a very thin filamentary coil. Assume, assume a single turn. The units are all cm. 4B illustrates a mutual inductance value in which the center of the Rx coil is changed according to the moving distance rho in parallel in the y direction in the drawing. Such a transmission / reception scheme may be an example of a structure in which a receiver is generally placed on a transmitter (eg, 5 cm distance when two coils coincide in the drawing) and wirelessly charges. As shown in the figure, the maximum mutual inductance value is shown when the centers of two coils coincide (y = 0), and the value decreases with increasing rho, and the mutual inductance value is 0 when the difference between centers is about 17cm. That is, the distance between the centers of the two coils is changed according to the change in the relative horizontal position of the two coils (moving one coil horizontally on the coil surface), and the area in which the magnetic field is coupled is changed, thereby changing the mutual inductance. For this reason, when the receiver moves in the actual charging area of the transmitter, the mutual inductance between the transmitting and receiving coils changes, thereby changing the optimum power transfer condition, so that the transmission and reception matching unit (Tx) can be used to obtain the maximum power transfer efficiency (η) according to the position. matching unit, Rx matching unit).

5 is an example of a coil structure in accordance with one embodiment of the present invention to have an electrically uniform mutual inductance. Referring to FIG. 5, the coil structure for having a uniform mutual inductance according to an embodiment of the present invention has four portions (N, r ₁ , r ₂ , r ₃ , r ₄ ) having different radii from the same center (N). ₁ , N ₂ , N ₃ , N ₄ ).

The outermost coil part N ₁ starts at one end receiving the input current (I ₀ ) and at least one time (eg, three times) from the outermost radius r ₁ (eg, 6.5 cm in Table 1 below). As part of loop coil (s) wound at intervals p ₁ (eg, 1.5 mm in Table 1 below), each loop coil of N ₁ has the same current direction as the input current. Here, the loop coils wound by the coil part N ₁ are described as being equally spaced, but the present invention is not limited thereto and may be wound at boiling intervals. Hereinafter, each of the other coils N ₂ , N ₃ , and N ₄ may also be formed of a coil wound multiple times, and in this case, the coils may be wound at equal intervals or boiling intervals.

Coil N nose extending connected to _one end of the part N ₂ is not smaller radius than the radius of the innermost coil of the coil N ₁ r ₂ single loop coil wound so as to have a (e. G., Under the reference 6cm in Table 1) It is preferable (plurally possible in some cases). The loop coil (s) of the coil portion N ₂ has a predetermined distance from the innermost coil of the coils of the coil portion N ₁ , and this interval is preferably different from the interval p ₁ of the coils of the coil portion N ₁ (in the case of Equal intervals available).

Coco connected to some N ₂ at the end N ₃ is part of a coil wound so as to have a (see 5.5cm in Table 1, e.g., below) the outermost small radius r ₃ than the inside radius r _2, the two coils constant Coils connected in parallel (eg 5mm in Table 1 below) in parallel (3 or more strands can be connected in some cases and the spacing between them is uneven), and coils of coil parts N ₁ and N ₂ They are formed once or multiple times so that the direction of current is reversed.

The coil part N _{4, which} is connected to the end of the coil part N ₃ again (the end of two connected coils), has a radius r ₄ smaller than the radius of the inner coil of the coil part N ₃ (eg, see 4.5 cm in Table 1 below). Coil wound to have two coils connected in parallel at regular intervals (e.g., see 15mm in Table 1 below). In some cases, more than three strands can be connected in parallel, and the spacing between them is uneven. It is formed in single or multiple times so that the current direction is the same as the coils of the coil parts N ₁ , N ₂ . FIG. 6 at an appropriate position, such as between the end of the coil portion N ₄ (the ends of two connected coils) and the portion where the coil portion N ₁ starts, or the end of the coil portion N ₄ or the portion where the coil portion N ₁ starts. As described above, the capacitor Cp may be connected for resonant frequency and impedance matching.

Input current (I ₀₎ it is applied to the coil N ₁ in Figure 5 the coil N aI ₀ and (1-a) in parallel to the coil of ₃ I ₀ flows is distributed, as in the nose βI ₀ in the parallel coil of some N ₄ And (1-β) I _{0 are} distributed and flowed. a and β can be positive or negative, and the magnitude of the absolute value is less than 2.

As described above, an example in which each coil part of a concentric circular shape is configured in the proposed coil structure of the present invention is not limited thereto, and each coil part may be configured in various concentric polygonal shapes, such as a rectangle and a hexagon. In addition, an example in which each coil part is made of a metal conductor wire such as a copper wire has been described as shown in FIG. 6. However, the present invention is not limited thereto. It is also possible. When using such a printed circuit board process or a semiconductor process, four coil parts (N ₁ , N ₂ , N ₃ , N ₄ ) are appropriately distributed and arranged on both sides of the substrate such as the printed circuit board or the semiconductor substrate. In this case, the connection between the coil parts formed in each layer may be connected through a via hole or the like.

In addition, in the arrangement of the respective coils (N ₁ , N ₂ , N ₃ , N ₄ ) as exemplarily illustrated in FIGS. 5 and 6, the present invention is not limited thereto, and the respective coils N ₁ , N ₂ , N ₃ , N ₄ ) does not matter in any position. In addition, there may be a part omitted from each of the coils (N ₁ , N ₂ , N ₃ , N ₄ ), where each coil portion may be properly connected between one end to the other end, the coil (N ₄ ) is It is also possible to arrange | position to outermost part rather than a center part (innermost area) like FIG. 5, FIG.

Table 1 Number of turn Pitch Radius Coil thickness Direction & connection N ₁ 3 1.5 mm 6.5 cm 0.64 mm Forward & series N ₂ One - 6 cm 0.64 mm Forward & series N ₃ 2 5 mm 5.5 cm 0.64 mm Reverse & parallel N ₄ 2 15 mm 4.5 cm 0.64 mm Reverse & parallel

7 is an example of an actual manufactured Rx coil according to an embodiment of the present invention. The Rx coil may be manufactured through a printed circuit board process, and the resonant frequency f _r is set to 6.78 MHz. In addition, the Rx coil may also be manufactured by various methods such as a thin copper wire or a semiconductor process. The Rx coil as described above is one example, and the coil structure of the present invention as shown in FIGS. 5 and 6 may be applied to the Rx coil. That is, both the transmission coil (Tx coil) and the reception coil (Rx coil) may be in the form of the coil structure of the present invention as shown in FIGS. 5 and 6, and only the transmission coil (Tx coil) as shown in FIGS. 5 and 6. It may be in the form of the coil structure of the present invention, and only the receiving coil may be in the form of the coil structure of the present invention as shown in FIGS. 5 and 6.

8 is a result of measuring mutual inductance (M ₁₂ ) between the transmission and reception coils of the wireless power transmission system according to an embodiment of the present invention.

As shown in FIG. 6, the transmitting coil (Tx coil) and the receiving coil (Rx coil) have a resonance frequency of 6.78 MHz, the end of the coil part N ₄ (the ends of two connected coils) and the coil part N ₁ start. Capacitor Cp may be connected to an additional 6.78 MHz resonant frequency as shown in FIG. 6 at an appropriate position, such as between the end of coil portion N ₄ or the portion where coil portion N ₁ starts.

In FIG. 8, graphs a and b show a transmission coil having a conventional coil structure using only N ₁ and N ₂ coil parts except N ₃ and N ₄ coil parts in the structure of FIG. 6 and a receiving coil having a structure as shown in FIG. 7. As the mutual inductance of, the case 1 (moves the center of the receiving coil in the y direction at the coordinates as shown in Figure 4) and case 2 (moves the center of the receiving coil in the x direction at the coordinates as shown in Figure 4). In FIG. 8, graphs c and d are mutual inductances between a transmitting coil having a structure as shown in FIG. 6 and a receiving coil having a structure as shown in FIG. 7. Direction) and case 2 (move the center of the receiving coil in the x direction horizontal to the coil plane at the coordinates as shown in FIG. 4).

As shown in FIG. 8, when the distance ρ (rho) between the centers and the centers of the two coils is changed in the charging zone, which is the colored portion of the graph a, the mutual inductance change is very large (for example, ( The maximum mutual inductance-minimum mutual inductance) / maximum mutual inductance> 0.2), and in the charging zone where the difference between the center and the center between the two coils is within 4 cm, the change in the mutual inductance is very small in graph c (e.g. , (Maximum mutual inductance min minimum mutual inductance) / maximum mutual inductance <0.2). In all cases, it can be seen that the mutual inductance value drops sharply out of the charging zone.

FIG. 9 illustrates a configuration in which the coil structure proposed in FIG. 5 is applied to a transmitter of a wireless power transmission system according to an embodiment of the present invention.

As shown in FIG. 5, four parts having different radii (r ₁ , r ₂ , r ₃ , r ₄ ) to have a uniform mutual inductance according to an embodiment of the present invention (N ₁ , N ₂ , N ₃₎ , N ₄ ), both ends of the coil proposed in the present invention may be connected to both ends of an impedance matching unit (Tx matching unit) of the transmitter to be used as a transmission coil (Tx coil), in which case the transmission coil (Tx coil) The proposed coil can be equivalent to the resistance R _p and the inductance L _p as a whole, and between one end of the proposed coil, which is a Tx coil, and one end of the transmitter's Tx matching unit, Capacitor C _p may be connected. The C _p is used for matching the resonant frequency and impedance, and in addition, the capacitor C _p may be connected in various forms such as between the end of the coil portion N ₄ and the portion where the coil portion N ₁ starts.

FIG. 10 shows a detailed configuration in which the coil structure proposed in FIG. 5 is applied to a transmitter of a wireless power transmission system according to an embodiment of the present invention.

As shown in FIG. 10, in a transmitter, a source coil (a magnetic inductance L _s in an equivalent circuit and a resistor R _s ) is connected across an AC source signal Vs (voltage source, current source, or power source). Capacitor C _s can be connected to either end of the source coil and has a capacitor C _p , which is a transmit (resonant) coil spaced apart from the source coil by magnetic coupling. One proposed coil (magnetic equivalent inductance L _p , equivalent resistance R _p ) is provided.

The source coil and the transmit (resonant) coil (Tx coil) are not directly connected, but are separated by a magnetic field, and mutual inductance M ₁ between the source coil and the transmit (resonant) coil (Tx coil) By controlling the impedance matching to function as an impedance matching unit (Tx matching unit). In addition, the capacitor C _S between one end of the AC source signal Vs and one end of the source coil may be used for resonance with the transmission (resonance) coil of the source coil. This is not necessary.

FIG. 11 shows another specific configuration in which the coil structure proposed in FIG. 5 is applied to a transmitter of a wireless power transmission system according to an embodiment of the present invention.

As shown in FIG. 11, in the transmitter, the transformer primary side (magnetic inductance L _s1 in the equivalent circuit, R _s1 in the equivalent circuit) is connected across the AC source signal Vs (voltage source, current source, or power source), and the transformer secondary side is connected. (in the equivalent circuit the magnetic inductance L _T1, resistors R _T1) of transmission (resonance) coil (Tx coil) across the capacitor C _p is in the proposed coil (equivalent circuit having both ends self-inductance L _p, the resistance R _p ). Here, the transformer functioning as an impedance matching unit may be a structure in which primary and secondary coils are wound around an air core structure, or primary and secondary coils in a material containing a magnetic material, such as a ferrite core. This may be a wound structure.

FIG. 12 shows another specific configuration in which the coil structure proposed in FIG. 5 is applied to a transmitter of the wireless power transmission system according to an embodiment of the present invention.

As shown in FIG. 12, in the transmitter, a capacitor C _m1 functioning as an impedance matching unit is connected across the AC source signal Vs (voltage source, current source, or power source), and the capacitor is connected in parallel. It is also possible to equip the proposed coil with magnetic current (magnetic inductance L _p , equivalent resistance R _p ) with C _p as a transmitting (resonant) coil (Tx coil).

FIG. 13 shows another specific configuration in which the coil structure proposed in FIG. 5 is applied to a transmitter of a wireless power transmission system according to an embodiment of the present invention.

As shown in FIG. 13, in the transmitter, an inductor L _m1 functioning as an impedance matching unit is connected across an AC source signal Vs (voltage source, current source, or power source), and a capacitor is connected in parallel. It is also possible to equip the proposed coil with magnetic current (magnetic inductance L _p , equivalent resistance R _p ) with C _p as a transmitting (resonant) coil (Tx coil).

In addition to the method of FIGS. 10 to 13 for such impedance matching, a matching circuit using various combinations of coils, transformers, capacitors, and inductors may be used.

14 illustrates a configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention. As described above, the coil structure shown in FIG. 7 or the proposed coil structure shown in FIG. 5 may be applied to the Rx coil described below.

As shown in Fig. 14, in a receiver, a receiver (resonance) coil (Rx coil) of a receiver coupled to a transmit (resonant) coil (Tx coil) and mutual inductance M ₁₂ (magnetic inductance L ₂ in an equivalent circuit). , Resistance R ₂ , capacitance C ₂ ) and an Rx matching unit for impedance matching connected at both ends thereof, and a load (impedance Z _L ) is provided at both ends of the Rx matching unit. Connected to form a structure that consumes power. The load (impedance Z _L ) may be a circuit for charging the battery or operating the device. C ₂ is used to adjust the resonant frequency and impedance matching of the Rx coil.

15 shows a detailed configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

As shown in Fig. 15, in a receiver, a receiving (resonant) coil Rx coil (self-inductance L ₂ , resistance R ₂ , capacitance C ₂ ), which is a receiving self resonant coil, A load coil (magnetic inductance L _L in the equivalent circuit, R _L in the equivalent circuit) coupled with the magnetic coupling thereof, and a capacitor C _L may be connected to either end of the load coil. A load (impedance Z _L ) is connected to both ends of the coil (or both ends via the capacitor C _L ) to form a structure that consumes power. The capacitor C _L between one end of the load coil and one end of the load (impedance Z _L ) can be used for matching the resonant frequency or impedance of the load coil of the source coil. This is not necessary and may be removed in some cases. In this case, the impedance matching may be performed by adjusting the mutual inductance M _L between the Rx coil and the load coil to function as an Rx matching unit.

16 shows another specific configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

As shown in Fig. 16, in a receiver, both ends of a receiving (resonant) coil (Rx coil) (self-inductance L ₂ , resistance R ₂ , capacitance C ₂ ) in a receiving self resonant coil To the transformer primary side (magnetic inductance L _T2 in the equivalent circuit, R _T2 in resistance) and the load across the transformer secondary side (magnetic inductance L _L2 in the equivalent circuit, R _{L2 in} resistance) (or both ends via capacitor C _L2 ) (Impedance Z _L ) is connected to form a structure that consumes power. Capacitor C _L2 between one end of the transformer secondary and one end of the load (impedance Z _L ) can be used for impedance matching, which is not necessary and can be removed in some cases. Here, the transformer functioning as an impedance matching unit may be a structure in which primary and secondary coils are wound around an air core structure, or primary and secondary materials in a material including a magnetic material, such as a ferrite core. It may be a structure in which the side coil is wound.

17 shows another specific configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

As shown in Fig. 17, in a receiver, both ends of a receiving (resonant) coil (Rx coil) (self-inductance L ₂ , resistance R ₂ , and capacitance C ₂ ) are self-resonant coils. An inductor L _m2 which functions as an impedance matching unit is connected, and a load (impedance Z _L ) is connected to both ends of the inductor L _m2 (or both ends via the capacitor C _m ) to consume power. Achieve. Capacitor C _m between one end of inductor L _m2 and one end of load (impedance Z _L ) can be used for impedance matching, which is not necessary and can be eliminated in some cases.

18 shows another specific configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

As shown in Fig. 18, in a receiver, both ends of a receiving (resonant) coil (Rx coil) (self-inductance L ₂ , resistance R ₂ , and capacitance C ₂ ) in a self-resonant coil are received. The capacitor C _m , which functions as an impedance matching unit, is connected, and a load (impedance Z _L ) is connected to both ends of the capacitor C _m to form a structure that consumes power.

19 shows another specific configuration of a receiver of a wireless power transmission system according to an embodiment of the present invention.

19, the receiver (Receiver) is a receiving (resonant) coil (Rx coil) which is a self-resonant coil (self-inductance L ₂ in the equivalent circuit, the resistance R ₂ , the capacitance C ₂ ) both ends The inductor L _m2 , which functions as an impedance matching unit, is connected, and a load (impedance Z _L ) is connected to both ends of the inductor L _m2 to form a structure that consumes power. This is a case where the capacitor C _m is removed from FIG. 17.

FIG. 20 is an example in which the structures of FIGS. 11 and 15 are combined.

As shown in FIG. 20, in the transmitter, the transformer primary side (magnetic inductance L _s1 in the equivalent circuit and the resistance R _s1 ) is connected across the AC source signal Vs (voltage source, current source, or power source), and the transformer secondary side is connected. (in the equivalent circuit the magnetic inductance L _T1, resistors R _T1) of transmission (resonance) coil (Tx coil) across the capacitor C _p is in the proposed coil (equivalent circuit having both ends self-inductance L _p, the resistance R _p ). Here, the transformer functioning as an impedance matching unit may be a structure in which primary and secondary coils are wound around an air core structure, or primary and secondary coils in a material containing a magnetic material, such as a ferrite core. This may be a wound structure.

Also, in the receiver, the receiving (resonating) coil (Rx coil) of the receiver (coupled with the mutual inductance M ₁₂ ) and the inductance M ₁₂ (magnetic inductance L ₂ in the equivalent circuit, the resistance is R ₂ , the capacitance is C ₂ ) and a load coil (magnetic inductance L _L in the equivalent circuit, R _L in the equivalent circuit) coupled to the magnetic coupling, and any of the load coil One end of the capacitor C _L may be connected, and a load (impedance Z _L ) is connected to both ends of the load coil (or both ends via the capacitor C _L ) to form a structure that consumes power. The capacitor C _L between the load coil and the load (impedance Z _L ) can be used for matching the resonant frequency or impedance of the load coil of the source coil, which is not necessary and Can be removed accordingly. In this case, the impedance matching may be performed by adjusting the mutual inductance M _L between the Rx coil and the load coil to function as an Rx matching unit.

As described above, in the short range wireless power transmission system according to the present invention, the arrangement of the receiver and the transmitter within the wireless power transmission distance having a uniform mutual inductance within 20% without a separate additional circuit using a single coil as shown in FIG. Free positioning is possible so that the center can be horizontally shifted relative to the center (allowing vertical position change within a certain distance), and the position of the vertical position where the relative center position is horizontally different (within a certain distance) Allow) It is possible to provide power or charge for the operation of each device by receiving power wirelessly from each of the multiple devices at the same time with each receiving coil. As the position between the transceivers is changed as described above, the system does not have to use an adaptive impedance matching circuit, thereby reducing the complexity of the system and configuring the system at a low cost.

Coil structure having a uniform mutual inductance may have a variety of forms, in particular, the coil structure as shown in Figure 5 proposed in the present invention uses a plurality of coils connected in series, each coil (N ₁ , N ₂ , N ₃ , N ₄ ,) may be connected at equal intervals or boiling intervals, there are also a structure in which a plurality of coils are connected in parallel, such a parallel structure may be a coil in which the current flows in the direction opposite to the input current direction, the input current direction The coil may be a current flowing in the same direction. In the arrangement of the respective coils N ₁ , N ₂ , N ₃ , and N ₄ as illustrated in FIGS. 5 and 6, the present invention is not limited thereto, and the coils N ₁ , N ₂ , and N ₃ are not limited thereto. , N ₄ ) does not matter in any position.

Such a coil structure increases the magnetic field of at least the weak magnetic field (central in the proposed coil structure), thereby increasing the magnetic field as a whole, around the coil structure (within a certain distance from the center), for example (maximum mutual inductance-minimum). The mutual inductance can be maintained to satisfy the mutual inductance) / maximum mutual inductance <0.2. This is not done by changing the shape of the coil, but is obtained by adjusting the arrangement of the coil. This was confirmed through simulation results, as shown in FIG. 21. That is, FIG. 21 is a simulation result of the magnetic field H _z at a height of 1 cm from each coil structure (H ₁ , H ₂ , H ₃ ), and the graph H ₃ removes N ₃ and N ₄ from the structure of FIG. 5. The result of the time, the graph H ₂ is the result when N ₄ is removed from the structure of FIG. 5, and the graph H ₁ is the same as that of FIG. 5. As can be seen in FIG. 21, H ₂ and H ₃ have a large magnetic field difference near the 5 cm moving distance parallel to the magnetic field of the center (radial displacement = rho = 0) in the y direction, but in the case of H ₁ It can be seen that the magnetic field is very large in the center and the magnetic field decreases and increases with the position moved in parallel in the y direction. As shown in FIG. 21, the magnetic field of the periphery where the magnetic field is weaker than the center may be reduced in the case of H ₁ than in H ₂ or H ₃ , but this is merely an example, and each coil N ₁ , N ₂ , N ₃ , N The magnetic field in the periphery may increase or decrease depending on the arrangement of ₄ ,) or the number of turns of the coil.

By utilizing the coil structure having such a uniform mutual inductance, even if the mutual position of the transceiver is changed, it has a constant mutual inductance or performance index, so that an impedance matching circuit suitable for a predetermined mutual inductance may be configured in the transceiver. That is, there is no need to change the appropriate impedance matching according to the transceiver position. 9 to 20, the impedance matching circuit has various configurations.

In addition, multiple loads, such as when the relative center position horizontally different (allowing vertical position changes within a certain distance) simultaneously receive power wirelessly with each Rx coil from each receiver of a plurality of devices. When the input impedance (Z _in ) of the transmitter may vary depending on the number and position of the Rx coil, but impedance matching by the application of a transmission coil (Tx coil) having a uniform mutual inductance as in the present invention Can be easily implemented.

For example, for such multiple loads, since the input impedance Z _in is changed according to the number of receivers or Rx coils, the input impedance Z _in sensing transmitter ( The variation of the load according to the quantity is sensed through not shown in the figure, and the input impedance Z _in according to the quantity is independent of each position of the multiple loads (receiver or Rx coil). ) Can be simply implemented to achieve impedance matching.

In addition, as shown in FIG. 10, by inserting a separate transmission coil, the transmission coil may be appropriately designed to always have high efficiency even at the maximum number of loads or less, and thus impedance matching for multiple devices may be performed.

In the conventional non-uniform mutual inductance structure that does not have a uniform mutual inductance as in the prior art, there is a problem in that a plurality of loads cannot be supported by one transmitter because mutual inductances by individual receivers are different and mutual inductances are large. As shown _{in the} figure, the input impedance (Z _in ) sensing circuit (not shown) simply senses the load variation according to the quantity and adjusts the input impedance accordingly so that the resistance value and the inductance of the Tx matching unit of the transmitter are adjusted. By controlling the value or the capacitance value so that impedance matching can be performed, it is possible to transmit and receive wireless power at the maximum power transfer efficiency η. Control of the resistance, inductance, or capacitance values of the Tx matching unit can be achieved by switching means (e.g. MOSFET, BJT, SCR, Thyrister) so that a separate resistor, inductor, capacitor, etc. can be added or removed from the circuit. And the like).

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

Claims (37)

A wireless power transmission system for transmitting and receiving power between a transmitter coil and a receiver coil of a receiver by magnetic coupling, The transmitter and the receiver are freely positioned at different center positions horizontally to wirelessly transmit and receive power through a predetermined range of uniform mutual inductance between the transmitting coil and the receiving coil. Wireless power transmission system. The method of claim 1, Wireless power transfer system characterized in that to charge the battery using the uniform mutual inductance through the receiving coil of the corresponding receiver at the same time in each of the multiple devices placed in a horizontally different position. The method of claim 1, The transmitter, A unit for adjusting input impedance matching of the transmitter according to multiple loads placed horizontally in different positions; And A sensing circuit that senses a change in the input impedance according to the loads and controls the unit to perform impedance matching for the multiple loads Wireless power transmission system comprising a. The method of claim 1, The transmitter, A unit for matching an input impedance of the transmitter between an alternating source signal and the transmitting coil, And wherein said input impedance matching is possible within a predetermined number of maximum multiple loads to be placed horizontally differently by said unit. The method of claim 4, wherein The source coil connected to the AC source signal is separated by the magnetic coupling with the transmitting coil, and the change of mutual inductance between the source coil and the transmitting coil according to the design of the transmitting coil is independent of the variation of the maximum number of multiple loads. Wireless input power transmission system, characterized in that capable of matching the input impedance. Between one end and the other end, a coil portion in which current flows in the direction of an input current applied at the one end; A coil portion connected to the coil portion through which current flows in a direction of the input current and concentric with the coil portion, in which current in a direction opposite to the input current flows; A coil structure for wireless power transfer according to mutual inductance with each target coil whose relative center position is horizontally different. The method of claim 6, The target coil is a coil structure, characterized in that the coil is a relatively horizontal center of position change, or a plurality of coils in which the relative center position is horizontally different. The method of claim 6, For each of the target coils, the coil structure to have a uniform mutual inductance in a predetermined range. The method of claim 6, The magnetic field of the central portion of the coil structure is relatively increased, the coil structure characterized in that it has a uniformity of mutual inductance with other coils. The method of claim 6, Coils constituting the coil structure is formed using a printed circuit board process or a semiconductor process, the coil structure characterized in that the coils formed by being distributed in multiple layers are connected through a via hole. The method of claim 6, Coil structure, characterized in that each coil portion of the coil structure wound in a concentric circle, or concentric polygonal shape. The method of claim 6, The coil unit in which current flows in the direction of the input current, And a coil part wound concentrically in the center direction a plurality of times so that current flows in the direction of the input current. The method of claim 6, A coil unit in which a current in a direction opposite to the input current flows, And a coil unit wound in parallel with at least two strands such that current flowing in a direction opposite to the input current flows. The method of claim 13, The coil structure wound by connecting two or more strands in parallel is coil structure, characterized in that wound single or multiple times. Between one end and the other end, including a coil portion in which current flows in the direction of the input current applied from the one end, A first coil part wound so as to be concentric in the center direction of a single time or a plurality of times so that current flows in the direction of the input current; The center coincides, and includes a second coil unit wound in concentric with two or more strands connected in parallel so that the current flows in the direction of the input current, Coil structure for wireless power transfer according to mutual inductance with each target coil whose relative center position is horizontally different. The method of claim 15, Coil structure, characterized in that the two coils are wound in parallel or concentrically connected to the two strands single or multiple times. The method of claim 15, The third coil part wound to form concentricity by connecting two or more strands in parallel so that a current in a direction opposite to the input current flows. Coil structure further comprising. The method of claim 15, The second coil portion is a coil structure, characterized in that disposed in the center or the outermost. A wireless power transmission system for transmitting and receiving power between a transmitter coil and a receiver coil of a receiver by magnetic coupling, The transmitting coil or the receiving coil may include: a first coil part wound so as to be concentric in a single direction or a plurality of times in a central direction so that a current flows in a direction of an input current applied at one end between one end and the other end; And A coil part connected to the first coil part through which current flows in the direction of the input current, the first coil part and the center coinciding and concentric, and a coil part through which current in a direction opposite to the input current flows or the center coincides And a coil part wound to form concentricity by connecting two or more strands in parallel so that a current flows in the direction of the input current. Wireless power transmission system for transmitting power to one or more receiving coils in which the relative center positions of the transmitting coils are horizontally different from each other. The method of claim 19, And for each of said receiving coils, has a uniform mutual inductance in a predetermined range between said transmitting coils. The method of claim 20, Wireless power transmission system for transmitting power without changing impedance matching at the transmitter or the receiver using the uniform mutual inductance. The method of claim 19, The transmitter, And means for impedance matching between said alternating source signal (Vs) and said transmitting coil for impedance of said transmitting coil. The method of claim 19, The transmitter, A source coil connected to an AC source signal, which is a voltage source, a current source, or a power source, but not directly connected to the transmitting coil, but separated and coupled to a magnetic field, wherein impedance matching is performed by mutual inductance between the source coil and the transmitting coil. Wireless power transmission system, characterized in that. The method of claim 19, And a capacitor between one end of the AC source signal and one end of the source coil. The method of claim 19, The transmitter, And a transformer for impedance matching, the primary side of which is connected to an AC source signal which is a voltage source, a current source, or a power source, and the secondary side of which is connected to the transmitting coil. The method of claim 19, The transmitter, And a capacitor for impedance matching connected between the AC source signal, which is a voltage source, a current source, or a power source, and the transmitting coil. The method of claim 19, The transmitter, And an inductor for impedance matching connected between the AC source signal, which is a voltage source, a current source, or a power source, and the transmitting coil. The method of claim 19, The receiver, Means for matching impedance to the load between the receiving coil and the load. The method of claim 19, The receiver, And a load coil connected to the load and spaced apart from each other without being directly connected to the receiving coil, and coupled to a magnetic field, wherein impedance matching is performed by mutual inductance between the receiving coil and the load coil. The method of claim 29, And a capacitor between one end of the load coil and one end of the load. The method of claim 19, The receiver, And a transformer for impedance matching, wherein the receiving coil and the primary side are connected and the load and the secondary side are connected to each other. The method of claim 31, wherein And a capacitor between one end of the secondary side and one end of the load. The method of claim 19, The receiver, And an inductor for impedance matching connected between a load and the receiving coil. The method of claim 19, The receiver, And a capacitor for impedance matching connected between a load and the receiving coil. The method of claim 24, And a capacitor between one end of the inductor and one end of the load. The method of claim 22, The transmitter, And a sensing circuit for sensing a load variation according to the quantity of the receiving coils, and controlling the means for impedance matching so that the impedance matching is performed through the sensing circuit so that an input impedance changed according to the load variation is adjusted. Wireless power transfer system characterized in that. Wirelessly transmitting power using an alternating source signal in a transmitting coil; And Receiving the power wirelessly at a receiving coil spaced apart from the transmitting coil by magnetic coupling, The transmitting coil or the receiving coil may include: a first coil part wound so as to be concentric in a single direction or a plurality of times in a central direction so that a current flows in a direction of an input current applied at one end between one end and the other end; And A coil part connected to the first coil part in which current flows in the direction of the input current, the first coil part and the center coincide with each other, concentric, and a coil part through which current in a direction opposite to the input current flows, or the center is coincident with And a coil part wound to form concentricity by connecting two or more strands in parallel so that a current flows in the direction of the input current. In the step of transmitting power wirelessly, the wireless power transmission method for transmitting power to each of the one or more receiving coils in which the relative center position in the transmitting coil horizontally different.

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