KR102524585B1 - Wireless charger and wireless power receiver - Google Patents

Abstract

The present disclosure discloses a method and structure for reducing electromagnetic radiation emission by shunting an in-phase current flowing in a wireless power transmitter and a wireless power receiver in a wireless charging system. A design methodology for a wireless charger to uniformly supply power at various locations and loads is disclosed.
An embodiment of the present disclosure features a large charging area for simultaneous charging of a plurality of mobile devices, providing high efficiency in various positions and directions of mobile devices, providing uniform power, and emitting a small amount of electromagnetic radiation from a transmitting coil and a receiving coil. to be

Description

Wireless charger and wireless power receiver {Wireless charger and wireless power receiver}

The present disclosure relates to a device for wireless power transfer (WPT), and more particularly a wireless charging system capable of simultaneously charging a plurality of mobile devices. Mobile devices are charged using magnetic field coupling of transmitting and receiving resonators.

Multiple development groups are working on WPT systems for spatial freedom of energy transmitters and receivers. The design, theoretical analysis, geometric optimization and common optimization approaches using multi-ply spirals or spiral coils with multiple turns have been addressed in the prior art for coils coupled in various geometries. . Optimization of power induction in a coil without using shielding elements and without applying a wireless charging system has also been analyzed in the prior art. A method of providing a uniform magnetic coupling between a transmitting coil and a receiving coil based on a size of a transmitting coil much larger than a size of a receiving coil has also been described in the prior art. It has already been demonstrated that the uniform magnetic coupling of the transmit and receive coils enables power transmission with uniform power transmission efficiency (PTE).

Wireless power transmission technology has been developed to realize convenient charging of a built-in battery of a mobile or wearable electronic device or a power supply source of the device. Wireless chargers with wireless power transmission technology typically operate in the range of 100 kHz to 100 MHz.

A mobile device that can conveniently be charged wirelessly has a battery pack and a receiving coil fixed therein. When the mobile device is placed close to the transmitting coil of the wireless charger, it is charged. An induced electromotive force is formed in the receiving coil by a magnetic field formed in the transmitting coil, and the electric power generated by the electromotive force charges the mobile device.

The most common wireless power charging scheme is a star topology network. A wireless charger interacts with one or more mobile devices for simultaneous charging. Wireless coupling is achieved through a power transmission resonator and a power reception resonator, and a magnetically coupled induction coil connects the power transmission resonator and power reception resonator. The power source is connected to the power transmitting resonator, and the power receiving resonator is connected to the rectifier to convert the receiving side energy from AC to DC.

A disadvantage of a wireless charger that can have a wide charging range and can be charged regardless of the position or direction of the power receiving resonator is that a large amount of conducted and radiated electromagnetic radiation (EMI) is emitted. A wireless charger with a wide charging range uses a high switching voltage and high current in a primary coil, which may cause a large amount of EMI and adversely affect other electronic products due to EMI. .

The present application provides a wireless charger and a wireless power receiver capable of reducing electromagnetic radiation emission by shunting a current of the same phase flowing through a wireless power transmitter and a wireless power receiver in a wireless charging system to a protection element.

A wireless charger according to some embodiments may include a transmission coil, a conductive protection element, and an impedance matching circuit connecting the transmission coil and a power source, and the impedance matching circuit is connected in parallel with the transmission coil to It may include at least two capacitors connected to the ground of the power source and the protection device.

In one embodiment, at least one tap of the transmission coil may be connected to the ground of the protection element and the power source.

In one embodiment, the at least one tap may be connected to the ground of the protection element and the power source through a galvanic connection or a capacitive connection.

In one embodiment, the capacitive connection may be formed by lumped capacitor elements or by mutual capacitance between the at least one tap and the protection element.

In one embodiment, the at least one tap may include a middle tap of the transmitting coil.

In one embodiment, a magnetic resonance absorption element positioned between the transmission coil and the protection element may be further included.

In an embodiment, a resonant frequency of the magnetic resonance absorption element may be equal to a frequency at which electromagnetic radiation emitted by the transmission coil peaks.

In one embodiment, the protection element may be created using at least one of a copper material and a ferrite material.

In one embodiment, the distance between the conductive turns of the transmission coil may decrease as the distance from the central portion of the transmission coil to the outer edges increases.

In one embodiment, the radius of curvature of the transmission coil turn is maximum at the outer periphery and may decrease towards the central portion of the transmission coil.

A wireless power receiver according to some embodiments may include a receiving coil and an impedance matching circuit connecting the receiving coil and a load, and the impedance matching circuit is connected in parallel with the receiving coil to the receiving coil. It may include at least two parallel capacitors connecting to the ground of the load.

In one embodiment, a protection element made of a conductive material may be positioned between the receiving coil and the load.

In one embodiment, the protection element may be created using at least one of a copper material and a ferrite material.

In one embodiment, at least two inductors may be connected in series between the at least two connections between the at least two series capacitors and the load, respectively, and a point between the at least two series capacitors and the at least two inductors may be defined as the At least two capacitors connected to the ground of the load may be further included.

In one embodiment, a rectifier may be connected to the impedance matching circuit.

In one embodiment, the receiving coil includes a plurality of conductive turns, and outer dimensions of the receiving coil may be maximized within an effective surface of the wireless power receiver.

In a wireless charging system according to some embodiments, the wireless power transmission unit may include a transmission coil, a power source, a protection element, and an impedance matching circuit connecting the transmission coil and the power source, and the impedance matching The circuit may include at least two capacitors connected in parallel with the transmitting coil to connect the transmitting coil to the ground of the power source and the protection element. The wireless power receiver may include a receiving coil, a load, and an impedance matching circuit connecting the receiving coil and the load, wherein the impedance matching circuit is connected in parallel with the receiving coil to connect the receiving coil to a ground of the load It may include at least two capacitors that A wireless charging system may include a wireless power transmitter and a wireless power receiver.

1 is a diagram showing an equivalent circuit of a wireless charging system according to an embodiment.
2 is a diagram of parameter models and dimensions of a transmitting coil and a first protection element according to an embodiment.
3 is a diagram illustrating a wireless power receiver and internal components thereof according to an embodiment.
4 is a view showing a structure of a wireless charging system viewed from the side according to an embodiment.
5 is a view illustrating a structure of a wireless charging system viewed vertically and horizontally when a wireless power receiver is positioned above a wireless power transmitter according to an embodiment.
6A and 6B are diagrams illustrating current distribution when the wireless power receiver is located at the center of the transmission coil in FIG. 6A and at the periphery of the transmission coil in FIG. 6B according to an embodiment.
7A and 7B are methods for reducing the total thickness of a wireless power transmitter according to an embodiment. In FIG. 7A, the first protection element is made of a copper material, and in FIG. 7B, the first protection element is made of a copper-ferrite material. It is a drawing showing a case where it has been made.
FIG. 8 is a diagram for indicating a location where a transmission coil is connected to a ground of a power source and a first protection element, and showing an enlarged view of the location where the transmission coil is connected, according to an exemplary embodiment.
9A and 9B are diagrams showing spectra of measured values of in-phase voltages in a transmission coil according to whether a shunt capacitor is connected to a ground of a power source and a first protection device, according to an exemplary embodiment. 9A shows a case of not being connected, and FIG. 9B shows a case of being connected.
10A and 10B show an equivalent circuit showing that a power source ground and a center tap of a transmission coil are connected according to an embodiment, with a galvanic connection in FIG. 10A and a capacitive connection in FIG. 10B. It is a diagram represented by a capacitive connection.
11A and 11B are diagrams showing an asymmetric structure in FIG. 11A and a symmetric structure in FIG. 11B in relation to the type of transmission coil structure according to an embodiment.
12 is a graph showing, through comparison, that an EMI radiation level is reduced by using a center-tap connection of a transmitting coil according to an embodiment.
13 is a circuit for connecting a capacitor 2C _2P to the ground of a load in a wireless power receiver according to an embodiment.
14a and 14b, according to an embodiment, in FIG. 14a, the capacitor 2C _2P is not connected to the ground of the load, and in FIG. 14b, the capacitor 2C _2P , C _3P and the ferrite bead L _2S are the load When connected to the ground, it is a diagram showing the spectrum of the measured values of voltage and current in the receiving coil.
15A to 15C are diagrams illustrating a self-resonant absorbing element positioned between a transmitting coil and a first protection element for reducing EMI radiation levels according to an embodiment. Figure 15a shows a view looking down obliquely from above, Figure 15b shows a view looking down from a vertical top, and Figure 15c shows a view viewed from the side.
FIG. 16 is a graph comparing EMI radiation between the presence and absence of a magnetic resonance absorption element in a power transmission unit according to an exemplary embodiment.
17A and 17B are graphs showing correlations of impedances of wireless power transmitters for correct and incorrect implementations of hybrid impedance matching circuits.
18 is a diagram illustrating experimental results of prototypes of a wireless power transmitter and a wireless power receiver according to positions of a wireless power receiver according to an embodiment.
19 is a flowchart of a method of designing a wireless power transmitter according to an embodiment.

Hereinafter, with reference to the accompanying drawings, embodiments will be described in detail so that those skilled in the art can easily practice them. However, the present disclosure may be embodied in many different forms and is not limited to the embodiments described herein. And in order to clearly describe the present disclosure in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Terms used herein may be used to describe various elements, but elements should not be limited by the terms. Terms are only used to distinguish one component from another.

Throughout the specification, when a part is said to be "connected" to another part, this includes not only the case where it is "directly connected" but also the case where it is "electrically connected" with another element interposed therebetween. . In addition, when a part is said to be “connected” to another part, it includes a case where a part is in a state capable of performing data communication through signal transmission and reception with another part.

In addition, when a certain component is said to "include", this means that it may further include other components without excluding other components unless otherwise stated.

The accompanying drawings may be schematically drawn to explain the embodiments, and some dimensions may be exaggerated for clarity. Similarly, a significant portion of the drawings may be arbitrarily represented.

The term “module” used in this specification should be interpreted as including software, hardware, or a combination thereof, depending on the context in which the term is used. For example, the software may be machine language, firmware, embedded code, and application software. As another example, the hardware may be a circuit, processor, computer, integrated circuit, integrated circuit core, sensor, micro-electro-mechanical system (MEMS), passive device, or combination thereof.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present disclosure. The terms used in this application have been selected as currently widely used general terms as much as possible while considering the functions in the present disclosure, but they may vary depending on the intention of a person skilled in the art, case law, or the emergence of new technologies. In addition, in a specific case, there is also a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the invention. Therefore, terms used in the present disclosure should be defined based on the meaning of the term and the general content of the present disclosure, not simply the name of the term.

Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

The embodiments described in this specification and the accompanying drawings are intended to explain the present disclosure through some of various embodiments of the present disclosure, and the present disclosure is not limited only to the embodiments described in this specification and the accompanying drawings.

A wireless power transmission unit used in this specification may include a wireless charger and a power source, and a wireless power receiving unit may include a receiving coil, an impedance matching circuit, and a load. The wireless charger may include an impedance matching circuit, a transmission coil, and a protection device. A wireless charger can be a separate device that can be connected to or disconnected from a power source. For example, a wireless charger may be connected to a power source for wireless charging.

The wireless power receiver may represent electrical, electronic, battery operated mobile or other devices. The load may be a battery or battery pack of a mobile device or other device. The wireless power receiver may be charged by receiving power formed by a magnetic field combination of the wireless power transmitter and the wireless power receiver. The wireless power receiver may be composed of a “wireless power receiver” and a load. The wireless power receiver may include a receiving coil and an impedance matching circuit. The wireless power receiver may be a separate device that can be connected to or separated from a load. For example, a wireless power receiver may be connected to a load to charge the load.

In this specification, the protection element connected to the ground and the transmission coil of the power source in the wireless power transmitter is referred to as a "first protection element", and the protection element for protecting internal components in the wireless power receiver is referred to as a "second protection element". refer to

The “first impedance matching circuit” referred to in this specification refers to an impedance matching circuit connected between a power source and a transmitting coil in a wireless power transmitter, and a “second impedance matching circuit” connected between a load and a receiving coil in a wireless power receiver. Refers to the impedance matching circuit.

In one embodiment, to charge the battery of the mobile device, the user may directly place the battery on the wireless charger or place the mobile device on the wireless charger. Therefore, the size of the wireless charger, specifically the power transmission resonator, is very important. A larger power transmit resonator can accommodate a larger transmit power and allow a greater number of mobile devices to be charged simultaneously. For example, a user may connect a battery or a mobile device to a wireless power receiver and then place the wireless power receiver connected to the battery or mobile device on a wireless charger.

When the wireless power receiver is placed on the wireless charger, the receiving coil and the transmitting coil may be coupled by magnetic flux passing through them. Therefore, the magnetic flux generated by the transmitting coil structure causes a current in the receiving coil, and energy can be transmitted to the wireless power receiving unit. The wireless power receiving unit may include a rectifier connected to an output terminal of the receiving coil and may include a power management circuit including a battery charging circuit. Specifically, a rectifier may be installed to perform AC-DC conversion before the current induced in the receiving coil reaches the load.

In one embodiment, a wireless charging system may include a wireless power transmitter and a wireless power receiver.

In one embodiment, the impedance matching circuit of the receiving coil includes at least two capacitors connected in parallel to the receiving coil, and the capacitors may connect the receiving coil to the ground of the wireless power receiver.

A power source provides a switching voltage and high current to the transmit coil. A large-scale transmitting coil induces both conducted and radiated electromagnetic emissions by connecting the transmitting coil structure to a protection element through at least two capacitors and shunting the in-phase current flowing through the transmitting coil structure. can reduce

The impedance matching circuit of the transmitting coil may define the change in impedance seen by the transmitting side according to the load of the wireless power receiving unit.

In one embodiment of the transmitting coil structure, mutual inductance may be spatially set to be independent of the position of the transmitting coil. The distance between the conductors of the transmitting coil decreases from the central part of the coil to the outer part. A curvature radius of a transmission coil turn may be maximum at an outer edge and may decrease toward a central portion.

In one embodiment, a center tap of the transmitting coil may be connected to the protection element and may also be connected to the ground of the power source.

In this specification, for convenience, “transmitting coil” is referred to as “TX coil”, “receiving coil” is referred to as “RX coil”, and “wireless power transmitter” is referred to as “TX unit” ”, “wireless power receiver” is referred to as “RX unit”.

The word “load” used herein may refer to a battery or battery pack of an electronic device. To charge the battery of an electronic device, a user must place the electronic device on a wireless charger surface. Therefore, the size of a wireless charger can be a significant issue. If the size of the wireless charger is large, more power can be supplied and a plurality of electronic devices can be charged at the same time. Various embodiments of the present disclosure will be described in more detail with drawings.

1 is a diagram showing an equivalent circuit of a wireless charging system according to an embodiment.

In one embodiment, an impedance matching circuit may be included in the TX unit 110 and the RX unit 120. In this specification, the impedance matching circuit of the TX unit 110 will be referred to as a first impedance matching circuit, and the impedance matching circuit of the RX unit 120 will be referred to as a second impedance matching circuit.

In one embodiment, the TX unit 110 may include a wireless charger 115 and a power source 111 .

In one embodiment, the TX unit 110 may include a power source 111, a TX coil 112, and a first impedance matching circuit 113. The power source 111 may be connected to the TX coil 112 through a first impedance matching circuit 113 . The current I _TX generated by the power source 111 may be converted into a current I _{TX _ COIL} by the first impedance matching circuit 113 . The first impedance matching circuit 113 may include at least two series capacitors 2C _1S and at least two capacitors 2C _1P connected to the TX coil 112 . A parallel capacitor 2C _1P can connect the TX coil 112 to the ground 114 of the power source and to the first protection element 130 . Capacitor 2C _1P is also called shunt capacitor. A series capacitor 2C _1S may connect the TX coil 112 and the output terminal of the power source 111. The first impedance matching circuit 113 may provide optimum impedance matching between the power source 111 and the TX coil 112 . Although only two 2C _1S capacitors and two 2C _1P capacitors are shown in FIG. 1, it can be easily understood by those skilled in the art that the number of capacitors may vary depending on specific circumstances. The first protection element 130 is disposed under the TX coil 112 and will reduce electromagnetic radiation emitted by the TX coil 112 except for the active charging area formed by the structure of the TX coil 112. can

In one embodiment, the RX unit 120 may include an RX coil 121, a second impedance matching circuit 122, and a load 123. The RX unit 120 may include a wireless power receiver including an RX coil 121 and a second impedance matching circuit 122 and a load 123 . The wireless power receiver including the RX coil 121 and the second impedance matching circuit 122 may be a separate device that can be connected to or separated from the load 123 . For example, in order to charge the load 123, the wireless power receiver may be connected to the load.

In the RX unit 120, the RX coil 121 is inductively coupled to the TX coil 112, and electromagnetic radiation emitted from the TX coil 112 induces charging currents in the RX coil 121. can In the RX unit 120, the RX coil 121 may be connected to the load 123 through a second impedance matching circuit 122, and the second impedance matching circuit 122 includes a series capacitor 2C _2S and the RX coil 121 ) may include at least two 2C _2P capacitors connected in parallel. The load 123 may be charged using the charging current. A parallel capacitor 2C _2P can connect the RX coil 121 to the ground 124 of the load. The series capacitor 2C _2S may connect the output terminal of the RX coil 121 and the load 123. The second impedance matching circuit 122 may provide optimal impedance matching between the RX coil 121 and the load 123 . Although only two 2C _2S capacitors and two 2C _2P capacitors are shown in FIG. 1, it can be easily understood by those skilled in the art that the number of capacitors may vary depending on specific circumstances.

In one embodiment, the first impedance matching circuit 113 and the second impedance matching circuit 122 maximize power transmission efficiency by allowing resonance to occur between the TX coil 112 and the RX coil 121. can

In one embodiment, the capacitors of the first impedance matching circuit 113 may change the impedance of the TX coil 112 according to the impedance of the load 123.

In one embodiment, the capacitors of the second impedance matching circuit 122 may be selected to transform the impedance of the RX coil 121 into an optimal impedance for the load.

In one embodiment, when the RX unit 120 is positioned above the TX unit 110, the TX coil 112 and the RX coil 121 may be coupled to each other by magnetic flux. The magnetic flux generated in the TX coil 112 induces I _{RX_COIL} current in the RX coil 121 as shown _{in FIG} . 1 , and energy may be transferred to the load 123 .

In one embodiment, the first impedance matching circuit of the TX unit may include at least two shunt capacitors (2C _1P ) connected in parallel with the TX coil 112, and the TX coil 112 is connected to the output of the power source 111 It may include at least two series capacitors (2C _1S ) connected to the terminal. The shunt capacitor may connect the TX coil 112 to the ground of the first protection element 130 and the power source 111, and through this shunt the in-phase current flowing in the TX coil 112 to the protection element 130 ( shunt) to reduce electromagnetic radiation emitted by the TX coil 112.

In one embodiment, the first protection element 130 may be made of a conductive material such as a copper material and/or a ferrite material.

In one embodiment, in the first impedance matching circuit 113 of the TX coil 112, a 2C _1P capacitor is connected in parallel with the TX coil 112 to connect the TX coil 112 and the first protection element 130, , which shunts the in-phase current and reduces parasitic EMI emissions. Due to the existence of the first protection element 130, the electromagnetic field induced by the current of the TX coil 112 can be suppressed everywhere except where the RX unit 120 is located. As a result, the final electromagnetic field is concentrated around the RX unit 120, and a current can be induced in the RX coil 121 of the RX unit 120. The RX unit 120 may be located at any location and in any direction as long as it is within an active charging area by the TX unit 110. The TX coil 112 can emit electromagnetic radiation uniformly wherever the RX section 120 is located in an active charging area. The active charging area is defined by the structure of the TX coil 112, and can provide a constant impedance regardless of the position or direction of the load 123.

In one embodiment, the conductive wires of the TX coil 112 may be wound at specific intervals between the wires. The distance between the conductive wires of the TX coil 112 may decrease in a direction away from the central portion of the TX coil 112 to the outside.

In one embodiment, the TX coil 112 can form a helical form, but is not limited thereto. The distance between the conductive wires may decrease as the distance from the center of the TX coil 112 in a radial direction increases.

In one embodiment, the curvature radius of the turn of the TX coil 112 may be maximum at the outer edges and may decrease towards the center.

In one embodiment, the TX coil 112 may be a planar coil fabricated on a single or multi-layer PCB. A planar coil may consist of a set of several layers. Each layer in a set may contain the same pattern of turns. All layers included in one set may be connected to each other by a plurality of vias, and may be configured as a solid conductive coil having the same thickness as the thickness of the one set.

In one embodiment, the first impedance matching circuit 113 has a structure symmetrical with respect to the output terminal of the power source 111, and the center point of the first impedance matching circuit 113 is the ground 114 of the power source 111 can be connected with

In one embodiment, the active charging area, which refers to an area where wireless charging is possible, formed by the TX coil 112 may maintain a constant impedance regardless of the location or direction of the load 123 in the active charging area.

In one embodiment, electromagnetic radiation emitted from TX coil 112 may be constant within an active charging region. Emission of electromagnetic radiation by the TX coil 112 may be suppressed in a range other than the active charging area.

The RX unit 120 may further include a rectifier connected to the output of the RX coil 121 and the impedance matching circuit 122 in front of the load 123 . The rectifier may be configured to perform AC-DC conversion on the current induced in the RX coil 121 .

In one embodiment, RX coil 121 may include a plurality of conductive turns. The outer dimensions of the RX coil 121 may be maximized within the available surface of the RX section 120 . The density and structure of the turns may vary depending on the structure and power consumption of the RX unit 120 .

In one embodiment, the second impedance matching circuit 122 of the RX unit 120 may include at least two capacitors 2C _2P connected to the RX coil 121, and may include the RX coil 121 as a load ( 123) may include at least two series capacitors (2C _2S ) connected to each other.

In one embodiment, the wireless charging system composed of the TX unit 110 and the RX unit 120 may operate in a frequency range of 100 kHz to 100 MHz.

Figure 2 is a diagram of the parameter model and dimensions of the TX coil 112 and the first protection element 130 according to an embodiment.

를 획득할 수 있다. TX 코일(112)의 구조는 아래 더 자세히 묘사되어 있다.If the coupling coefficient k and Q-factors between the TX coil 112 and the RX coil 121 do not change with respect to the relative position of the RX section 120 on the TX section 110, at various coupling conditions of the TX coil and the RX coil Constant power efficiency η and constant input impedance

can be obtained. The structure of TX coil 112 is described in more detail below.

In one embodiment, the center of the conductive wire of TX coil 112 can be described by the following parametric model.

는 i번째 코일 전선의 곡률 반지름이고, α는 턴 비율을 나타내는 매개변수이다. shx와 shy는 각각 제 1 보호 소자(130)의 가로 및 세로 길이를 의미한다. TX 코일(112)의 N, lx_i, ly_i 및

와 같은 차원들은 최대의 효율을 전달할 수 있는지, 그리고 RX부(120)가 있을 수 있는 위치마다 균일(uniformity)한 효율을 전달할 수 있는지 라는 기준에 의해 최적화 될 수 있다. RX부(120)에서 RX 코일(121)의 차원 및 위치는 RX부(120)의 구조적 한계에 의해서 정의될 수 있다. Here, lx _N and ly _N correspond to the outermost dimension of the TX coil 112, and lx ₁ and ly ₁ correspond to the innermost dimension of the TX coil 112. N is the number of coil turns,

is the radius of curvature of the i-th coil wire, and α is a parameter representing the turn ratio. shx and shy mean the horizontal and vertical lengths of the first protection element 130, respectively. N of the TX coil 112, lx _i , ly _i and

Dimensions such as can be optimized based on whether maximum efficiency can be delivered and whether uniform efficiency can be delivered at each location where the RX unit 120 can be located. The dimensions and position of the RX coil 121 in the RX unit 120 may be defined by the structural limitations of the RX unit 120.

The existence of the first protection element 130 and the RX unit 120 can reduce the inductance of the TX coil 112 . Although the first protection element 130 does not have a large effect on loss, an eddy current induced in a lossy material of the RX unit 120 may dissipate energy. Therefore, the actual environment of the TX unit 110 may impose great limitations on power transfer efficiency (PTE).

Although the conductive turns of TX coil 112 in FIG. 2 are wound 5 times, this is just one example and may be fewer or more.

3 is a diagram showing the RX unit 120 and its internal components according to an embodiment.

In one embodiment, the second protection element 301 isolates the internal components 302 and 303 of the electronic device to which the RX unit 120 is coupled from the electromagnetic radiation emission of the TX coil 112 and the RX coil 121. ) may be installed under the RX coil 121. For example, the internal components 302 and 303 of the electronic device may be one or more micro circuits.

The internal components 302 and 303 may be isolated from electromagnetic radiation emitted from the TX coil 112 and the RX coil 121 through the second protection element 301 .

In one embodiment, the second protection element 301 may be made of a conductive material such as a copper material and/or a ferrite material.

In one embodiment, internal components 302 and 303 may be isolated from the electromagnetic radiation emissions of TX coil 112 and RX coil 121 by a conductive structure such as a battery or battery pack.

4 is a view showing a structure of a wireless charging system viewed from the side according to an embodiment. “a” means the distance from the TX coil 112 to the first protection element 130, and “h” means the distance from the RX unit 120 to the TX coil 112. The existence of the first protection element 130 and the RX unit 120 can reduce the inductance of the TX coil 112 . The second protection element 301 described in FIG. 3 may be positioned adjacent to the RX coil 121 as shown in FIG. 4 . The drawings can be largely divided into three parts. A wireless charger 115 including a TX coil 112 and a first protection element 130, a wireless power receiver including an RX coil 121 and a second protection element 301, and other internal components 302, 303), an electronic device including a battery, and a total of three parts. A wireless charger, a wireless power receiver, and an electronic device may be separate devices. To charge the battery of the electronic device, the electronic device may be connected to a wireless power receiver and placed on the wireless charger 115 .

5 is a diagram illustrating a structure of a wireless charging system viewed vertically and horizontally when the RX unit 120 is positioned above the TX unit 110 according to an embodiment. The same components are shown in correspondence so that you can compare how each component of the wireless charging system appears when viewed vertically and horizontally when viewed from the side. Although the number of conductive turns of the TX coil 112 in FIG. 5 is 5, this is only an example and may be less or more than that. In the figure in which the TX coil 112 and the RX unit 120 are overlapped in FIG. 5 according to an embodiment, the vertical length of the TX coil 112 and the vertical length of the RX unit 120 appear almost similar, but the TX coil The length and width of 112 may be relatively greater than the length and width of the wireless power receiver 120 .

6A and 6B show current distribution when the RX unit 120 is in the center of the TX coil 112 in FIG. 6A and on the outside of the TX coil 112 in FIG. 6B according to an embodiment. it is a drawing

에 의해 정의될 수 있다. 일반적으로 TX 코일(112)의 인덕턴스 및 Q-팩터는 RX부(120)가 TX 코일(112)의 가운데에서 모서리 쪽으로 이동함에 따라 증가한다. 이는 렌츠의 법칙에 따라 설명될 수 있다. RX부(120) 표면의 와전류(eddy currents)는 TX 코일에 의해 유도된 마그네틱 플럭스를 보상할 수 있다. 와전류는 RX부(120)의 배터리, 메인 보드, 프레임 등의 전도성 표면 위를 흐를 수 있다. 대표적인 위치에 RX부(120)가 각각 위치할 때 RX부(120) 위에서의 표면 전류 분포가 도 6a 및 도 6b에 나타난다. 도 6a에서 RX부(120)(전자 디바이스와 결합되어 있다)는 TX 코일(112)의 중간 부분에 위치하고, 도 6b에서는 RX부(120)가 TX 코일(112)의 외곽 부분으로 이동해 있다. 도 6a 및 도 6b에서 RX부(120) 표면에서 어둡게 칠해진 부분은 RX부(120) 몸체 표면의 전류 밀도가 높음을 의미하고, 밝은 부분은 RX부(120)의 몸체 표면의 전류 밀도가 낮음을 의미한다. RX부(120)가 서로 다른 여러 위치에 있을 때 유도된 전류의 분포가 서로 다른 것은, RX부(120)가 TX 코일(112)의 어느 위치에 있느냐에 따라 TX 코일(112)의 인덕턴스가 달라진다는 점을 설명해 준다. RX부(120)가 TX 코일(112)의 중간 부분에 위치할 때, TX 코일(112) 중간 부분에서의 마그네틱 필드는 대부분 RX부(120)의 표면에 수직이다. 이 경우 전류 분포는 RX부(120)의 모서리를 기준으로 대칭일 수 있다.Parameters may be changed in the TX coil 112 of the TX unit 110 according to a change in the relative position of the RX unit 120 with the TX coil 112. The dependence of the coupling coefficient k on the position of the RX unit 120 is the TX coil 112 design parameters lx _i , ly _i ,

can be defined by In general, the inductance and Q-factor of the TX coil 112 increase as the RX section 120 moves from the center to the corner of the TX coil 112. This can be explained according to Lenz's law. Eddy currents on the surface of the RX unit 120 may compensate for magnetic flux induced by the TX coil. Eddy currents may flow on conductive surfaces such as a battery, a main board, and a frame of the RX unit 120 . The surface current distribution on the RX unit 120 when the RX unit 120 is located at a representative position, respectively, is shown in FIGS. 6A and 6B. In FIG. 6A, the RX unit 120 (coupled with the electronic device) is located in the middle of the TX coil 112, and in FIG. 6B, the RX unit 120 is moved to the outer portion of the TX coil 112. In FIGS. 6A and 6B , the darkly painted part of the surface of the RX unit 120 means that the current density of the body surface of the RX unit 120 is high, and the bright part means that the current density of the body surface of the RX unit 120 is low. it means. The reason why the distribution of the induced current is different when the RX unit 120 is located in different positions is that the inductance of the TX coil 112 varies depending on where the RX unit 120 is located on the TX coil 112. explains that When the RX unit 120 is located in the middle of the TX coil 112, the magnetic field at the middle of the TX coil 112 is mostly perpendicular to the surface of the RX unit 120. In this case, the current distribution may be symmetrical with respect to the corners of the RX unit 120.

In the outer portion of the TX coil 112, the magnetic field mainly consists of a tangent component and a non-uniform normal component. When the RX unit 120 is located near the corner of the TX coil 112, the main part of the magnetic flux is concentrated in the middle of the TX coil 112, and the eddy current density becomes lower and can be asymmetrical. Compared to the case where the RX unit 120 is located in the middle of the TX coil 112, the field component perpendicular to the plane of the RX unit 120 is concentrated in a smaller area, resulting in less magnetic flux. and the inductance of the TX coil 112 may increase.

7A and 7B are methods for reducing the total thickness of the TX unit 110 according to an embodiment. In FIG. 7A, when the first protection element 130 is made of a copper material, in FIG. 7B, the first protection element ( 130) is a diagram showing a case in which copper-ferrite materials 701 and 702 are formed.

In one embodiment, the copper-ferrite material can further reduce the total thickness of the TX section 110 (it can be seen in FIG. 7B that the distance A is reduced by using the copper-ferrite material).

Isolation of the TX unit 110 from surrounding materials is possible by using various materials when configuring the first protection element 130, as shown in FIGS. 7A and 7B. In particular, in order to reduce the total thickness of the TX unit 110, a thin ferrite film material may be used instead of other conductive materials. A ferrite thickness of 0.5mm is enough to produce a shielding efficiency of 20dB.

Parameter changes of the TX unit 110 and the RX unit 120 according to the change of the first protection element 130 are shown in Table 1. According to the results of Table 1, using ferrite and copper materials and using a thin TX coil 112 (d = 0.1 mm) can reduce the total thickness of the TX section 110 to 5.7 mm. Installing the first protection element 130 at a distance of a = 5 mm from the TX coil 112 and using only copper material reduces the magnetic inductance L1 by 57% and the coupling factor k by 40% compared to the case without the protection element can give you Installing the first protection element 130 at a distance from the TX coil 112 by a = 5 mm and using only ferrite material can reduce the Q-factor by 24% compared to the case without the first protection element 130 there is. Reducing the thickness d of the TX coil 112 from 2 mm to 0.1 mm does not affect the parameter. Using the first protection element 130 using only a ferrite material makes the wireless charging system efficient, but the fact that the magnetic inductance of the TX coil 112 affects an external metal material (eg a metal table) should be considered. It's something to do. As described above, it is desirable to devise a suitable protection device in consideration of the influence of parameters, the total thickness of the TX unit 110, and the like.

Changes in TX and RX parameters according to changes in the first protection element parameter
name No protection element for TX coil 0.1mm
copper protection element
a=10mm
d=2mm 1mm
copper protection element
a=5mm
d=2mm 1mm
ferrite protection element
a=5mm
d=2mm 0.5mm
ferrite protection element
a=5mm
d=2mm 0.5mm
ferrite protection element
a=5mm
d=0.1mm 0.1mm copper and 0.5mm ferrite protection element
a=5mm
d=0.1mm L ₁ , uH 2.03 1.26 0.87 2.7 2.6 2.6 2.4 Q ₁ 144 164 138 110 109 108 103 k 0.25 0.18 0.15 0.27 0.26 0.26 0.26 U 32.7 25.5 17.9 29.7 28.8 28.7 27.2

8 is to show a location where the TX coil 112 is connected to the ground 114 of the power source 111 and the first protection element 130 according to an embodiment, and to show an enlarged view of the connected location. it is a drawing According to one embodiment, connecting the TX coil 112 to the ground 114 of the power source and the first protection element 130 is performed by using the first impedance matching circuit 113 as shown in FIG. 1 . Capacitors 2C _1S and 2C _1P of the first impedance matching circuit 113 may be located in the region 801 of FIG. 8 .

In one embodiment, looking at the right figure showing an enlarged view of the position where the TX coil 112 is connected to the ground 114 of the power source and the first protection element 130, the capacitor 2C _1P is connected to the TX coil 112 It can be seen that the ground 114 of the power source is connected in parallel and the capacitor 2C _1S connects the TX coil 112 and the power source 111 in series.

9A and 9B show the measured value of the in-phase voltage at the TX coil 112 depending on whether the shunt capacitor is connected to the ground 114 of the power source and the first protection element 130, according to an embodiment. It is a diagram showing the spectrum for 9A shows a case of not being connected, and FIG. 9B shows a case of being connected. A comparison of FIGS. 9A and 9B confirms the effect of whether or not the shunt capacitor is connected on the reduction of in-phase noise. As shown in FIG. 1 , the TX coil 112 may be connected to the ground 114 of the power source 111 and the first protection element 130 using a capacitor 2C _1P . According to the results shown in FIGS. 9A and 9B , in the case of FIG. 9A in which the shunt capacitor is connected, it can be confirmed that the EMI noise spectrum is reduced by at least 10 dB in the 90 MHz frequency range or higher.

10A and 10B are equivalent circuits showing that the power source ground 114 and the center tap 1001 of the TX coil 112 are connected according to an embodiment, galvanic connection in FIG. 10A and capacitance in FIG. 10B. It is a diagram showing sex connection. The center tap 1001 of the TX coil 112 may be connected to the first protection element 130, and the first protection element 130 may be connected to the ground 114 of the power source, thereby reducing EMI radiation. can make it As a connection method, various connection methods including the galvanic connection of FIG. 10A or the capacitive connection of FIG. 10B may be used. Through various connection methods, the in-phase current can be shunted before passing through the TX coil 112, and parasitic radiation emission from the TX coil 112 can be attenuated. The transfer of differential output power from the power source 111 to the TX coil 112 is not affected by the various connection methods. Therefore, PTE does not decrease.

In one embodiment, the capacitive connection may be formed through lumped capacitor elements or by mutual capacitance between the center tap 1001 and the first protection element 130 . This is represented in the circuit as C _1C (1002).

In one embodiment, multiple connection taps” between the TX coil 112 and the first protection element 130 are formed through capacitive connections. A multiple connection tap is a term used to refer to a case where multiple taps are used. There may be more than one tap on the TX coil 112 and may include the center tap of the TX coil 112 .

11A and 11B are views illustrating an asymmetric structure in FIG. 11A and a symmetric structure in FIG. 11B in relation to the type of structure of the TX coil 112 according to an embodiment. The structure of TX coil 112 can be based on various types, including asymmetric helical coil 1101, symmetric helical coil 1102. In each case, single or multiple center taps 1001 may be positioned to optimize the amplitude and phase balance of the voltages at the TX coil 112 pins.

In one embodiment, the center tap 701 of the TX coil 112 is connected to the ground of the power source 111 to reduce EMI radiation.

12 is a graph showing through comparison that the EMI radiation level is reduced by using the center-tap connection of the TX coil 112 according to an embodiment. Graph 1201 shows a case where the TX coil 112 does not have a center tap 1001, and graph 1202 shows a case where the TX coil 112 has a center tap 1001. In graph 1201, which is a case without the center tap 1001, there are two peaks in total, one peak occurring at 100 to 120 MHz and one peak occurring at 180 to 200 MHz. In graph 1202, which is a case where there is a center tap 1001, there is one peak at 180 to 200 MHz. Through this, it can be confirmed that the center tap 1001 of the TX coil 112 can reduce the EMI radiation level by at least 40 dB in the frequency range of 100 to 120 MHz.

13 is a circuit for connecting the capacitor 2C _2P to the ground 124 of the RX unit 120 in the RX unit 120 according to an embodiment. In an embodiment for further reducing EMI, 'capacitor 2C _2P ' is connected to 'ground 124 of RX unit 120', and shunt capacitor C _3P and ferrite bead L _2S are connected in FIG. 13 As shown, it can be realized through an equivalent circuit that connects.

14a and 14b, according to an embodiment, in FIG. 14a, the capacitor 2C _2P is not connected to the ground of the load, and in FIG. 14b, the capacitor 2C _2P , C _3P and the ferrite bead L _2S are the load When connected to the ground 114, it is a diagram showing the spectrum of measured values of voltage and current in the RX coil 121. This shows the effect of connecting the shorting capacitor C _3P and the ferrite bead L _2S on common mode noise reduction. According to the results shown in FIGS. 14A and 14B , the EMI noise spectrum can be reduced by at least 20 dB at 150 MHz and by at least 30 dB at 350 to 500 MHz.

15A to 15C are diagrams illustrating a magnetic resonance absorption element 1501 positioned between the TX coil 112 and the first protection element 130 to reduce the EMI radiation level according to one embodiment. FIG. 15A shows a view looking down obliquely from above, FIG. 15B shows a view looking down from a vertical top, and FIG. 15C shows a view looking down from a cross-section view. 15C is a cross-section of section A-A. The magnetic resonance absorption element 1501 can suppress the parasitic resonance of the TX coil 112 by absorbing all or some peaks of the EMI radiation.

FIG. 16 is a graph comparing electromagnetic (EMI) radiation between the presence and absence of the magnetic resonance absorption element 1501 in the TX unit 110 according to an exemplary embodiment. The effect of the magnetic resonance absorption element 1501 on EMI radiation can be confirmed. The Q-factor of the magnetic resonance absorption element 1501 can affect the EMI radiation reduction efficiency. In the graph, curve 1602 represents an over-damping resonance structure and curve 1603 represents an under-damping resonance structure. , curve 1604 represents an optimally damping resonance structure. As can be seen in FIG. 16, the 412 MHz magnetic resonance absorption element of the curve 1601 can suppress parasitic resonance by about 20 dB. The difference is indicated at 1605.

The TX unit 110 may further include a magnetic resonance absorption element 1501 disposed under the TX coil 112 and may be used to reduce electromagnetic radiation emitted from the TX coil 112 .

The resonance frequencies of the magnetic resonance absorption element 1501 are tuned to be equal to the frequencies of the peaks of the electromagnetic radiation emitted by the TX coil 112, so that the magnetic resonance absorption element 1501 absorbs the peaks of the electromagnetic radiation at the resonance frequencies. can absorb Peaks of electromagnetic radiation may negatively affect internal components of the electronic device being charged and are therefore desirable to be reduced or eliminated. The magnetic resonance absorption element 1501 may be formed in the form of a split-ring resonator, a complementary resonance spiral, a resonance spiral, a complementary split-ring resonator, or other metamaterial structure. can

17A and 17B are graphs showing correlations of impedances of wireless power transmitters for correct and incorrect implementations of hybrid impedance matching circuits. The maximum PTE of the inductively coupled TX coil 112 and RX coil 121 is possible at the optimal load impedance. To analyze these parameters, consider two mutually coupled induction coils with inductances L ₁ and L ₂ , intrinsic losses R ₁ and R ₂ , and mutual inductance M. As can be seen in FIG. 1 , it can be assumed that the RX coil 121 is connected to a load having a complex impedance Z ₂ . That is, let the complex impedance viewed from the RX coil 121 to the second impedance matching circuit 122 and the load 123 be Z ₂ . Optimal impedance matching Z ₂ satisfies the resonance condition in the RX coil 121, and the maximum power transmission efficiency is Z ₂ as follows Satisfied in _opt :

Meanwhile, the figure of merit U is used in the equation below for convenience.

이다. 한편 ω 는 TX부(110) 및 RX부(120)가 동작하는 주파수이다. 수학식 4로 표현되는 최적의 Z₂ opt에서 전력 송신의 최대 효율은where k = the inductive coupling coefficient of the coil

am. Meanwhile, ω is the frequency at which the TX unit 110 and the RX unit 120 operate. Optimal Z ₂ expressed by Equation 4 The maximum efficiency of power transmission at opt is

am. The input impedance of the TX coil 112 at optimal load is

am. As the input impedance Z _{TX _ IN _ COIL} and the optimal impedance Z ₂ are defined in Equations 4 and 7, the first and second impedance matching circuits 113 and 122, as shown in FIG. It is necessary to match the impedances for the power source 111 and the load 123. Elements of the impedance matching circuit for the RX unit 120 can be calculated as follows using the rectifier input impedance Z _RECT .

은 RX 코일(121)에 병렬로 연결된 커패시터 C2P의 임피던스이고, Y=-1/ωC_2S는 부하(123)에 직렬로 연결된 커패시터 C_2S의 임피던스이다. 수학식 9의 값을 가지는 직렬 소자는 커패시터 또는 인덕터일 수 있다. 수학식 8에서 마이너스 근을 가지는 것은 커패시터를 임피던스 매칭 회로의 분로 소자

로 이용할 가능성을 의미할 수 있고, 여기서 X_NEG는 수학식 8에서의 마이너스 근을 의미한다. 유도된 Y값이 마이너스인 경우, 직렬 커패시터 값은 이다. where X=-

is the impedance of the capacitor C2P connected in parallel to the RX coil 121, and Y=-1/ωC _2S is the impedance of the capacitor C _2S connected in series to the load 123. A series element having the value of Equation 9 may be a capacitor or an inductor. Having a negative root in Equation 8 makes the capacitor a shunt element of the impedance matching circuit.

, where X _NEG means a negative root in Equation 8. If the derived value of Y is negative, the series capacitor value is

Standards applicable to the serial/parallel mixed element of the second impedance matching circuit 122 in the RX unit 120 are as follows.

은 직렬 임피던스 매칭, 즉 C_2P=0과 대응할 수 있다. 조건

가 아닌 경우에는 제 2 임피던스 매칭 회로(122)의 직병렬 혼합 소자가 이용될 수 있다. condition

may correspond to series impedance matching, that is, C _2P =0. condition

If not, the serial/parallel mixing element of the second impedance matching circuit 122 may be used.

The operation of the power source 111 is defined by the input impedance Z _{TX _ IN} of the TX unit. The first impedance matching circuit 113 of the TX coil 112 can be designed from the following equation.

로 정의할 수 있다.Here, X may be a reactive component of a device connected in parallel to the TX coil 112, and Y may be a reactive component of a device connected in series to the power source 111. In Equation 11, the sign of the root of X can determine whether the type of device connected in parallel will be a capacitor or an inductor. A value of a series element can be obtained from Equation 12, and this series element can be a capacitor or an inductor. The presence of a negative root is related to the possibility of using the capacitor as a parallel element of the first impedance matching circuit 113.

can be defined as

식으로부터 산출될 수 있다.where X _NEG is the negative root of equation (11). When the calculated value of Y is negative, the value of the series capacitor is

can be calculated from Eq.

를 제공한다.Equation 13 is the maximum that can be matched with a specific TX coil 112

provides

,

에 근접하여 작동할 때 만족된다. 여기서 Z_{TX _ IN}의 실수부는

가 증가함에 따라 감소하며,In one embodiment, referring to FIG _. 1 , it can be seen that the real part _of Z _{TX_IN} is inversely proportional to the impedance Z _RECT of the load 123 . _An increase _in Z _RECT can decrease Z _{TX_IN} . _A decrease _in Z _RECT can increase Z _{TX_IN} . The required Z-change is the series resonance of the TX impedance matching circuit 113.

,

is satisfied when operating close to Here, the real part of Z _{TX _ IN} is

decreases as increases,

can be expressed as

가 증가함에 따라 Z_{TX _ IN}이 감소하는 결과가 그래프 1702에서 나타나므로, 상기 검토한 대로 부등식

을 만족함을 확인할 수 있다. 도 17b를 보면, 제 1 임피던스 매칭 회로(113)가 올바르게 작동하지 않는 경우, 일 실시예에 따른 스미스 도표에서 Z_{TX _ IN}의 변화가 수직에 가까움(1702)을 확인할 수 있다. 도 17b에서

가 증가함에 따라 Z_{TX _ IN}은 증가하다가 감소하는 결과가 그래프 1704에서 보이는바

을 만족하지 않음을 확인할 수 있다. 즉 Z_{TX _ IN} 임피던스의 실수부는 증가하는

에 대하여 일정하지 않은(non-uniform) 의존성을 나타냄을 알 수 있다.The dependence of the input impedance Z _{TX_IN} of the TX unit ₁₁₀ on Z _RECT is two examples when the hybrid impedance matching circuit works correctly in FIG. 17a and when _the hybrid impedance matching circuit does not work correctly in FIG. 17b. can be found in Referring to FIG _{. 17A} , when the first impedance matching circuit 113 operates correctly, it can be confirmed that the change of Z _{TX_IN} is close to horizontal (1701) on a Smith chart according to an embodiment. In Figure 17a

As Z TX_IN increases, the result of decreasing Z _{TX _ IN} is shown in graph 1702, so as reviewed above, the inequality

can be confirmed to be satisfied. Referring to FIG _. 17B , when the first impedance matching circuit 113 does not operate correctly, _it can be seen that the change of Z _{TX_IN} is close to vertical (1702) in the Smith diagram according to an embodiment. in Figure 17b

The graph 1704 shows that as Z _{TX _ IN} increases and then decreases as

is not satisfied. That is, the real part of Z _{TX _ IN} impedance increases

It can be seen that it represents a non-uniform dependence on .

은 전압 정재파 비(voltage standing wave ratio)이고, 반사계수

는 뒤의 수학식 15에 Z_{TX _ IN}에 관한 식으로 정의되어 있다.18 is a diagram showing experimental results of prototypes of the TX unit 110 and the RX unit 120 according to positions of the RX unit 120 according to an embodiment. According to the experimental results, the maximum PTE of the TX coil 112 is 90% and PTE > 84% regardless of the position and orientation of the RX unit 120 within the active charging area. Looking at the possible positions of the mobile device, the dX position is from -37 mm to +37 mm at positions 1801, 1802, and 1803 when the mobile device is vertical, and the dY position at positions 1804, 1805, and 1806 is from -30 mm when the mobile device is horizontal. +30mm.

is the voltage standing wave ratio, and the reflection coefficient

Is defined as _an expression _for Z _{TX_IN} in Equation 15 below.

Meanwhile, an analytical solution to the optimal impedance matching circuit in Equations 8, 9, 10, and 11 can provide ideal matching and maximum power transmission efficiency. However, changes in coil parameters at various locations of the mobile device may change impedance matching and efficiency.

Matching and efficiency levels at all possible locations of the RX unit 120 can be predicted by _{the difference} between Z _{TX_IN} and optimal Z _{TX_IN} using the reflection coefficient Γ. Γ can be calculated from the following equation.

A quantitative assessment of the acceptable level of TX coil 112 parameter variation can be made using a precise analysis of circuit input impedance versus coil parameter variation. The reflection coefficient variation is defined as:

Here, Z _IND is the impedance induced by the RX coil 121 and can be expressed as follows.

Consider the microscopic changes around the optimal matching and maximum PTE points.

The change in the real part R1+ReZ _IND of the TX coil 112 impedance is directly included in Equation 18, but the change in the imaginary part wL ₁ +ImZ _IND of the TX coil 112 impedance is the coefficient Q ₁ /k ² Q ₂ It is included with and is affected by the parameters of the TX coil 112 and the RX coil 121.

When the RX coil 121 is matched as defined in Equations 8 and 9, and the load (Z _RECT ) is constant, the RX coil 121 parameter changes very little and the resistance change of the TX coil 112 is worth ignoring.

in any position

In this case, the reflection coefficient change in Equation 18 can be simplified as follows.

As a result, a small coupling factor (k<0.1) can make the TX coil 112 react very sensitively to changes in inductance.

19 is a flowchart of a method of designing the TX unit 110 according to an embodiment. Methods based on increasing inductive coupling and Q-factor can be applied to improve power transmission efficiency. In the process, the design of the TX coil 112 is a trade-off between 'uniformity of inductive coupling' and 'change in inductance while the position of the RX unit 120 is relatively changed with respect to the TX coil 112' off) is there. Therefore, the evaluation criterion for the design of the TX coil 112 may be based on the position of the RX unit 120, the change in the input impedance of the TX coil 112 according to the load impedance, and the PTE.

로 나타낼 수 있고, 여기서

는 0.8 내지 0.9의 값을 가질 수 있는 파라미터로서 제 1 보호 소자(130) 및 RX부(120)의 존재로 인한 TX 코일(112) 및 RX 코일(121) 간의 상호 인덕턴스의 감소에 대해 정의한다. Step S110 of FIG. 19 is a step for determining an average inductive coupling coefficient. The average inductive coupling coefficient is the ratio of the surface area S _TX of the TX coil 112 to the surface area S _RX of the RX coil 121

can be expressed as, where

Is a parameter that may have a value of 0.8 to 0.9 and defines a reduction in mutual inductance between the TX coil 112 and the RX coil 121 due to the existence of the first protection element 130 and the RX unit 120.

Step S120 of FIG. 19 is a step for designing inner turns. The inner turn of the TX coil 112 is designed so that the change in inductance L ₁ of the TX coil 112 is minimized when the RX unit 120 is located in the middle of the active charging region and rotates in the middle. It can be. The length and width of the active charging area and the asymmetry of the RX coil 121 cause an unavoidable change in the coupling factor. These unavoidable changes may be minimized by adjusting the dimensions of the internal turns and .

에 의해서 정의될 수 있다. 최적의 턴 비율

는 0.55일 수 있다.Step S130 of FIG. 19 is a step for setting a turn ratio. If the RX unit 120 is located within a certain distance from the center of the active charging area, uniform coupling and uniformity of the input impedance of the TX coil 112 need to be maintained. The outer turns of the TX coil 112 need to be placed as close together as possible between turns to provide the least inductance change at the outermost possible locations of the RX section 120. In the previously mentioned parametric model of the TX coil 112, the uniformity is the turns ratio

can be defined by Optimal turn ratio

may be 0.55.

Step S140 of FIG. 19 is a step for determining the line width and the number of conductive turns. The line width and the number of conductive turns N of the TX coil 112 can be optimized based on the following considerations. While increasing N allows maintaining high coupling uniformity when the RX section 120 is in various positions, N is limited because it is limited to the minimum coil line width. On the other hand, reducing the coil line width reduces the average coupling factor and Q ₁ , and thus reduces the maximum efficiency. Increasing coil line width improves Q ₁ , but increases the change in TX coil 112 inductance when RX section 120 is located close to the edge of an active charging area. The line width and the number of conductive turns N of the TX coil 112 can be optimized considering these factors. Since the reduction in resistance loss of the TX coil 112 due to the increase in line width is relatively small, the Q-factor does not depend on the line width. This phenomenon is related to the fact that the flow of current on the surface of the conductor is not uniform and is greatest at the edge of the conductor. Mutual inductance between the TX coil 112 and the RX coil 121 is independent of the line width. Consequently, as the TX coil 112 resistance decreases, the efficiency increases according to equation (5).

15 mm인 경우는 k=0.129로 감소한다.Step S150 of FIG. 19 is a step for designing an external turn. The outer turns of the TX coil 112 should be rounded with the largest possible radius of curvature to increase the average coupling coefficient. For example, looking at FIG. 2, when it is formed as round as possible, k = 0.157, and only the corners are rounded.

In the case of 15 mm, it decreases to k=0.129.

Step S160 of FIG. 19 is a step for designing an impedance matching circuit. An optimal impedance matching circuit can be calculated using Equations 8, 9, 10, and 11. The calculated first and second impedance matching circuits 113 and 122 may provide optimal matching and maximum PTE. Effects of impedance matching and PTE change due to the position change of the RX unit 120 can be seen from Equation 18.

Due to the present disclosure, it is possible to reduce electromagnetic radiation emission outside the active charging area of a wireless charger, reduce parasitic radiation emission by a transmission coil, and prevent electronic devices from being interfered with by electromagnetic radiation emission. . Multiple mobile devices can provide maximum power transmission efficiency no matter where they are or in what direction.

The present disclosure enables the ultimate goal of a wireless charging system, such as freedom of space and location, and various charging environments. The disclosed resonator design provides an ergonomic solution for all wearable devices in the home or office, wireless power stations in public places such as restaurants, coffee shops, and libraries.

One embodiment provides high-efficiency wireless charging for multiple mobile and wearable devices including smartphones, smart watches, smart glasses, tablet computers and notebooks, etc. to provide.

The description of the present disclosure described above is for illustrative purposes, and those skilled in the art can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present disclosure. will be. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present disclosure may be indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof may be included in the scope of the present disclosure. should be interpreted as

Claims (16)

transmission coil;
A protective element made of a conductive material; and
An impedance matching circuit connecting the transmission coil and a power source,
The impedance matching circuit includes at least two capacitors and a third capacitor,
A first end of each of the at least two capacitors is connected in parallel with the transmission coil, and a second end of each is connected to each other, and each of the at least two capacitors connects a different tab of the transmission coil to the ground of the power source and the ground of the power source. Connect to the protection element,
A first end of the third capacitor is connected to a center tap of the transmitting coil, and a second end is connected to the ground of the power source and second ends of each of the at least two capacitors,
The wireless charger, wherein the at least two capacitors and the third capacitor reduce electromagnetic radiation emission by shunting an in-phase current flowing in the transmission coil to the protection element. delete According to claim 1,
At least one tap of the transmitting coil is connected to the ground of the protection element and the power source through a capacitive connection, wireless charger. According to claim 3,
Wherein the capacitive connection is formed by lumped capacitor elements or by mutual capacitance between the at least one tap and the protection element. delete According to claim 1,
Further comprising a self-resonant absorbing element positioned between the transmission coil and the protection element, the wireless charger. According to claim 6,
The resonant frequency of the magnetic resonance absorption element is the same as the frequency at which electromagnetic radiation emission by the transmission coil peaks. According to claim 1,
The protection element is produced using at least one of a copper material and a ferrite material, wireless charger. According to claim 1,
Characterized in that, the distance between the conductive turns of the transmitting coil decreases as the distance from the central portion of the transmitting coil to the outer edges increases. According to claim 1,
Characterized in that the radius of curvature of the transmitting coil turn is maximum at the outer edge and decreases towards the central portion of the transmitting coil, the wireless charger. delete delete delete delete delete A transmission coil, a power source, a protection element, and an impedance matching circuit connecting the transmission coil and the power source,
The impedance matching circuit includes at least two capacitors and a third capacitor,
A first end of each of the at least two capacitors is connected in parallel with the transmission coil, and a second end of each is connected to each other, and each of the at least two capacitors connects a different tab of the transmission coil to the ground of the power source and the ground of the power source. connected to the protection element;
A first end of the third capacitor is connected to a center tap of the transmitting coil, and a second end is connected to the ground of the power source and second ends of each of the at least two capacitors,
a wireless power transmission unit, characterized in that the at least two capacitors and the third capacitor reduce electromagnetic radiation emission by shunting the same-phase current flowing through the transmission coil to the protection element; and
A receiving coil, a load, and an impedance matching circuit connecting the receiving coil and the load,
The impedance matching circuit is a wireless charging system including a wireless power receiver, characterized in that it comprises at least two capacitors connected in parallel with the receiving coil and connecting the receiving coil to the ground of the load.

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