Wireless power transmission device having reduced mutual inductance variation

Abstract

A wireless power transmission device and an optimized structure thereof are disclosed. The device includes a coil and a magnetic core, and a spacing between coil winding turns is intentionally designed to be non-uniform in order to reduce variation in a mutual inductance value when positional misalignment occurs between a transmitting coil and a receiving coil. Self-inductance values of the transmitting coil and the receiving coil may be optimized within a specific low range, respectively, for system stability improvement, mounting space securement, cost efficiency, and the like. In addition, in order to improve performance and reduce costs, the magnetic core may be implemented in a hybrid structure in which magnetic materials having different characteristics are combined, or may be optimized to have a width smaller than the width of the coil. It is also possible to reduce the overall thickness of the device by integrating a connection wire into a coil layer without a separate wiring layer for the coil connection wiring. Through the optimization of these various structures, provided is a wireless power transmission device that is robust to position changes and has improved stability, efficiency, miniaturization, and economic feasibility.

Description

Wireless power transmission device with reduced mutual inductance variation

[0001] The present invention relates to the field of wireless power transfer (WPT) technology. More specifically, the present invention relates to a technology for securing stable power transfer performance by improving the problem of the mutual inductance value, which is a key performance indicator of the system, fluctuating depending on the relative position change (e.g., alignment error, distance change) between a transmitter and a receiver in a wireless power transfer system that transfers power in a non-contact manner using the principles of magnetic induction or magnetic resonance. In particular, the present invention relates to a wireless power transfer device in which the structure and design of a coil and / or a magnetic core are optimized so as to reduce the mutual inductance variation.

[0002] With the recent proliferation of electric vehicles (EVs), demand for wireless charging technology that allows for convenient automatic charging while parked is rapidly increasing. Furthermore, the application of wireless power transfer technology is expanding to diverse fields, including portable electronic devices like smartphones, industrial robots, and medical devices.

[0003] These wireless power transfer systems typically consist of a transmitter (e.g., a charging pad installed on the ground) that supplies power and a receiver (e.g., a current collector mounted on the underbody of a vehicle) that receives the power. Each component includes a coil and a magnetic core as core components to exchange energy via magnetic fields. When an alternating current flows through the transmitter coil, a time-varying magnetic field is generated. This magnetic field then links with the receiver coil, inducing a voltage and, thereby, transmitting power. The magnetic core plays a crucial role in shaping the magnetic field's path and concentrating the magnetic flux, thereby increasing power transfer efficiency.

[0004] However, the conventional wireless power transmission technology described above has several technical limitations and problems, and efforts are required to improve its performance, stability, and practicality.

[0005] Mutual inductance (M) fluctuation problem due to positional deviation: The performance of a wireless power transfer system is highly dependent on the degree of magnetic coupling between the transmitting and receiving coils, i.e., the mutual inductance (M). However, this M value varies very sensitively depending on the relative positions of the two coils, such as horizontal alignment (X, Y-axis errors), vertical distance (Z-axis, air gap), etc. In actual electric vehicle charging environments, it is difficult for users to park perfectly aligned every time, so misalignment between the transmitting and receiving pads inevitably occurs. Conventional coil designs often follow a method of maintaining a uniform gap between the winding strands, but this structure suffers from a problem in that the M value fluctuates greatly when positional deviation occurs. Large fluctuations in the M value change the system's resonant frequency and impedance, making stable control of the transmitting inverter difficult. This causes output instability, especially during battery charging where constant current (CC) / constant voltage (CV) control is required. This, in turn, causes serious problems such as reduced charging efficiency and charging time fluctuations, which undermine performance consistency.

[0006] The Difficulty of Optimizing Coil Self-Inductance (L) Values: To ensure stable resonance and efficient power transfer in the system, it is crucial to appropriately set the self-inductance (L) values ​​of each of the transmitter and receiver coils. However, the L value has a trade-off relationship with various factors such as system stability (e.g., securing bandwidth), component cost, and especially the mounting space occupied by resonant capacitors in the receiver, making it difficult to select the optimal L value that satisfies all conditions.

[0007] Limitations of Single-Material Magnetic Cores: Ferrite, a widely used magnetic core material, offers advantages in terms of cost and processability, but has performance limitations such as relatively low saturation flux density and low Curie temperature. To improve these limitations, amorphous or nanocrystalline alloys with high saturation flux density and excellent high-frequency characteristics have been proposed as alternatives. However, these materials themselves are expensive and difficult to process. In addition, high-performance crystalline materials, in particular, present difficulties in precisely controlling directionality due to magnetic anisotropy. Therefore, it has been difficult to satisfy high performance, cost efficiency, and excellent reliability with just a single type of magnetic material.

[0008] Inefficiencies in core size and pad structure: Furthermore, magnetic cores are often designed under the common assumption that they must cover the entire coil area for optimal performance. However, this may not always be optimal. Furthermore, using a separate wiring layer to connect the coil windings to external circuitry can unnecessarily increase the overall pad thickness, creating structural inefficiencies.

[0009] There is a high need for technological development for improved wireless power transmission devices and systems that address the problems of the above-mentioned conventional technologies, provide robust and stable performance in response to changes in position, and have an efficient and practical structure.

[0010] The present invention is intended to solve the problems of the prior art as described above, and the first technical task of the present invention is to solve the problem that when a positional deviation such as an alignment error or distance change occurs between a transmitter and a receiver in a wireless power transmission system, particularly an electric vehicle wireless charging system, the mutual inductance (M) value fluctuates greatly, thereby lowering the stability of power transmission and making it difficult to ensure consistency in charging performance.

[0011] In addition, the second technical task is to provide an improved method for setting the optimal self-inductance (L) value of the transmitting / receiving coil, taking into account the stability of the system, component cost, mounting space, and especially the capacitor space constraints within the receiving device.

[0012] Furthermore, the third technical challenge is to provide an improved core structure that can overcome the performance limitations (e.g., low saturation flux density, heat generation, etc.) or economic / technical shortcomings (e.g., high cost, difficulty in controlling anisotropy, etc.) of existing single-material magnetic cores.

[0013] In addition, the fourth technical task is to provide a method to further improve the performance of the system (e.g., increase the M value) or reduce the physical size (especially the thickness) of the entire device and reduce weight and cost by optimizing the size of the magnetic core or the coil and wiring structure.

[0014] In order to solve the above-mentioned problem, according to the present invention, a wireless power transmission device is provided, comprising: a coil composed of a plurality of windings; and a magnetic core arranged to be magnetically coupled to the coil, wherein at least a portion of the gap between the plurality of windings constituting the coil is set to be non-uniform so as to reduce the rate of change in the mutual inductance value between the alignment state and the positional deviation state between the coil and the opposing coil.

[0015] Preferably, the non-uniform spacing is set such that the spacing between the windings located at the center of the coil is relatively wider than the spacing between the windings located at the outer portion of the coil.

[0016] It is preferable that at least some of the windings in the edge region of the above coil be wound in a multilayer structure of two or more layers.

[0017] Preferably, the variation rate of the mutual inductance (M) value is 15% or less as defined by the following mathematical expression 1:

[0018] [Mathematical Formula 1]

[0019]

[0020] (However, Malignment is the mutual inductance value in a predefined alignment state, and Mdeviation is the mutual inductance value in a predefined maximum position deviation state.)

[0021] Preferably, the non-uniform gap is set to satisfy a preset minimum mutual inductance (M) value or more required for rated charging of the wireless power transmission device even in the maximum position deviation state.

[0022] The above coil may be a DD (Double-D) coil shape, and may be any one shape selected from the group of circular, square, hexagonal, or elliptical coil shapes.

[0023] Preferably, the wireless power transmission device is a transmitting device that transmits energy, and the magnetic inductance value of the coil is 100 uH or less.

[0024] Preferably, the wireless power transmission device is a receiving device that receives energy, and the magnetic inductance value of the coil is 60 uH or less.

[0025] The above magnetic core may be a hybrid magnetic core including a base magnetic portion; and a second magnetic portion combined with the base magnetic portion and having a different type of material than the base magnetic portion and having a higher permeability or higher saturation magnetic flux density characteristic.

[0026] The above base magnetic body part and the above second magnetic body part may be arranged adjacent to each other within the same plane or layer, or one part may be inserted within the other part.

[0027] The above base magnetic body part and the above second magnetic body part can be arranged in a form in which they are separated into different layers and stacked in the vertical direction or the left-right direction.

[0028] The above base magnetic body part and the above second magnetic body part can be processed into strip or block shapes, respectively, and arranged alternately or mixed in a predetermined pattern to be arranged three-dimensionally.

[0029] Preferably, the overall width of the magnetic core is formed smaller than the overall width of the coil, thereby improving the mutual inductance (M) value between the coil and the opposing coil.

[0030] It is preferable that the connecting wiring connecting the winding end of the coil and the external circuit is not formed in a separate wiring layer physically separated from the coil layer in which the coil winding is arranged, but is formed integrated with the coil winding within the coil layer, thereby reducing the overall thickness of the structure including the magnetic core and the coil layer.

[0031] The wireless power transmission device according to the present invention can provide the following excellent effects.

[0032] Enhanced Stability and Consistent Performance: The coil winding spacing non-uniformity design significantly reduces the variation in mutual inductance (M) values ​​even when positional deviations occur, significantly improving the stability of system control and providing consistent charging efficiency and speed under various conditions.

[0033] Optimized coil inductance design: By setting the self-inductance (L) values ​​of the transmitting and receiving coils within the optimal range by comprehensively considering stability, cost, and mounting space (especially the receiving capacitor space), stability can be secured while achieving system miniaturization and cost efficiency.

[0034] High-Performance / High-Efficiency Core Implementation: By adopting a hybrid magnetic core structure, the limitations of single materials can be overcome, resulting in superior magnetic and thermal performance, including reduced core loss, suppressed heat generation, and increased saturation flux density. This contributes to higher system efficiency and output.

[0035] Performance Improvement and Weight Reduction / Cost Reduction: By optimizing the core width to be smaller than the coil width, the mutual inductance (M) value can be further improved, while at the same time reducing the amount of core material used, resulting in weight reduction and cost reduction.

[0036] Reduced thickness and secured design flexibility: By optimizing the connection wiring structure and eliminating separate wiring layers, the overall thickness of devices such as wireless charging pads is drastically reduced, enabling slim designs and alleviating installation space constraints.

[0037] Comprehensive System Improvement: The combined effects of the above provide the foundation for implementing a next-generation wireless power transfer system that is insensitive to positional changes, stable, efficient, compact, lightweight, and economical.

[0038] FIG. 1 is a perspective view showing a schematic configuration of a wireless charging transmitting pad and a wireless charging receiving pad that can be used in a wireless power transmission system according to one embodiment of the present invention.

[0039] Fig. 2 is a plan view of an example of a wireless charging transmitting pad having a DD coil structure including two separate winding sections, and also shows the area of ​​a receiving pad placed overlapping thereon.

[0040] FIG. 3 is a plan view showing in detail one specific example of winding arrangement of a DD type coil to which a non-uniform winding spacing design according to the present invention is applied.

[0041] FIG. 4 is a plan view showing an example of a winding arrangement of a second embodiment of a DD type coil to which a non-uniform winding spacing design according to the present invention is applied, which is different from FIG. 3.

[0042] FIG. 5 is a plan view (top) and a side view (bottom) showing one embodiment of a hybrid magnetic core structure formed by combining different types of magnetic materials according to the present invention.

[0043] FIG. 6 is a perspective view showing the configuration of a wireless charging transmitting pad and receiving pad using a magnetic core optimized to a width smaller than the width of each coil according to the present invention.

[0044] FIG. 7 is a perspective view (top) and a side view (bottom) showing an example of a coil structure in which the coil winding and connection wiring are integrated without a separate wiring layer according to the present invention, thereby optimizing the overall thickness.

[0045] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. Identical or similar components are given identical or similar drawing reference numerals, and redundant descriptions thereof are omitted. In describing the embodiments disclosed in this specification, if a detailed description of a related known technology is judged to obscure the gist of the embodiments disclosed in this specification, the detailed description thereof will be omitted. The attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, and replacements included in the spirit and technical scope of the present invention.

[0046] Terms containing ordinal numbers, such as "first," "second," etc., may be used to describe various components; however, these terms are used solely to distinguish one component from another and are not limited to the components in question. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0047] The terms “comprises,” “includes,” or “has” as used herein should be understood to limit the presence of a feature, step, component, or combination thereof described in the specification, but not to exclude the possibility that one or more other features, steps, components, or combinations thereof may be present or added.

[0048] The term 'Wireless Power Transfer Apparatus' used in this specification should be understood to comprehensively refer to a device that performs the role of transmitting power wirelessly or receiving power wirelessly as an individual functional unit constituting a wireless power transfer system, unless the context clearly dictates otherwise.

[0049] More specifically, in the present specification and claims, depending on its implementation form, the 'wireless power transmission device' may be a 'transmitting apparatus' including a coil and related circuitry for wirelessly supplying energy (e.g., a charging pad, a power supply rail, etc.), or a 'receiving apparatus' including a coil and related circuitry for wirelessly receiving the energy and transmitting it to a load (e.g., a battery) (e.g., a current collector mounted on an electric vehicle, a mobile device, a robot, etc.).

[0050] Accordingly, when a particular component or technical feature of the present invention (e.g., a coil structure with non-uniform winding spacing and a magnetic core configuration related thereto as disclosed herein) is described as being applied to or incorporated into a "wireless power transmission device," this means that the component or feature may be applied to either a "transmitting device" or a "receiving device." That is, the present invention may be implemented in either or both of a transmitting device and a receiving device.

[0051]

[0052] FIG. 1 is a perspective view schematically showing the configuration of a wireless charging transmitting pad (100) and a wireless charging receiving pad (200) that can be used in a wireless power transmission system according to one embodiment of the present invention. As illustrated in FIG. 1, the wireless charging system includes a wireless charging transmitting pad (100) that is installed on the ground or a structure to transmit energy, and a wireless charging receiving pad (200) that is mounted on a vehicle or device to receive energy. The transmitting pad (100) includes a transmitting coil (110) and a transmitting core (120), and the receiving pad (200) includes a receiving coil (210) and a receiving core (220).

[0053] The transmitting pad (100) receives AC power from an external power source and generates a time-varying magnetic field in the transmitting coil (110). The transmitting core (120) is typically made of a magnetic material such as ferrite, and serves to guide the magnetic field generated from the transmitting coil (110) to be efficiently formed in a desired path (mainly in the direction of the receiving pad), concentrate the magnetic flux to strengthen the magnetic coupling, and reduce the leakage magnetic flux in unnecessary directions.

[0054] The receiving pad (200) is placed facing the transmitting pad (100) at a certain distance (air gap). When the time-varying magnetic field generated in the transmitting coil (110) passes (interlinks) through the receiving coil (210), an AC voltage and current are induced in the receiving coil (210) according to Faraday's law of electromagnetic induction. The receiving core (220) is also made of a magnetic material, and effectively collects the magnetic field entering the receiving coil (210) to increase the induction efficiency. The AC power induced in the receiving coil (210) is then converted into DC power in the form required by the load (e.g., battery) and supplied through a rectifier circuit, a DC-DC converter, etc. (not shown).

[0055] The performance of such a wireless power transfer system, especially the power transfer efficiency and transferable capacity, is largely dependent on the degree of magnetic coupling between the transmitting coil (110) and the receiving coil (210). This degree of coupling is represented by a parameter called mutual inductance (M), and a larger M value generally means higher efficiency and power transfer. However, this M value is not a fixed value, but has the characteristic of changing very sensitively depending on the relative position (alignment status, horizontal / vertical distance) of the transmitting pad (100) and the receiving pad (200). Since perfect alignment is difficult in an actual usage environment, the resulting positional deviation (misalignment) causes fluctuations in the M value, which makes it difficult to secure stable control of the system and constant charging performance.

[0056] Additionally, the self-inductance (L) values ​​of each coil, i.e., the inductance of the transmitting coil (LTx) and the inductance of the receiving coil (LRx), are important factors in setting the resonant frequency and impedance matching of the system. These L values ​​affect the electrical characteristics and component configuration of the system (e.g., the resonant capacitor capacitance).

[0057] In addition, the material selection, shape design, size, and internal structure of the magnetic core (120, 220) also have a great influence on the performance and efficiency of the entire system, such as magnetic flux path formation, M value and L value, core loss, heat generation, weight, and cost, as well as manufacturability.

[0058] Finally, the overall physical structure of the pad (100, 200), including the coil, core, connecting wire, etc., especially the thickness, is an important factor in determining the ease of installation and scope of application of the product.

[0059]

[0060] Fig. 2 is a plan view of an example of a wireless charging transmitting pad (100) having a DD (Double-D) coil structure including two separate winding sections (112, 114), and also shows an area of ​​a receiving pad (200) that is arranged to overlap thereon. Fig. 2 shows a first winding section (112) and a second winding section (114) of the transmitting pad (100) formed on a magnetic core (120), and an interval (G1, G2) between the winding strands is illustrated as an example inside the first winding section (112), and the receiving pad (200) is arranged on top so as to be magnetically coupled with the transmitting pad (100).

[0061] FIG. 2 is an exemplary plan view of a transmission pad (100) for explaining the principle of minimizing the variation of mutual inductance (M) through non-uniformity of coil winding spacing, which is one of the main features of the present invention. As illustrated, the transmission pad (100) according to one embodiment of the present invention may have a DD coil structure, which may include a first winding portion (112) and a second winding portion (114) that are arranged adjacent to each other on a magnetic core (120). For convenience of explanation, the drawing schematically illustrates a form in which a plurality of winding strands (turns) are wound inside the first winding portion (112) and the spacing (G1, G2) therebetween.

[0062] As mentioned above, in conventional coil designs, it has been common to maintain the spacing between the winding strands constituting each winding section (112, 114) as uniform as possible (i.e., G1 = G2 = constant value). Such uniformly spaced coils can have a high mutual inductance (M) value through high magnetic coupling when the transmitting pad (100) and the receiving pad (200) placed thereon are in ideal positions. However, when a relative positional deviation (misalignment) occurs between the transmitting pad (100) and the receiving pad (200), such as a misalignment that occurs when an actual vehicle is parked, the M value fluctuates significantly, causing serious problems such as unstable system control and deteriorating charging efficiency and speed consistency.

[0063] In order to solve this problem, the present invention has a key feature of intentionally designing the spacing between the winding strands constituting the coil to be non-uniform. The spacings G1 and G2 expressed in the first winding portion (112) of Fig. 2 exemplify this non-uniform spacing design. That is, not all winding spacings are the same, but the spacing at a specific location (e.g., G1) and the spacing at another location (e.g., G2) are designed to have different values. For example, the winding spacing of a specific part of the coil (e.g., the center or periphery of the loop) can be adjusted to be wider or narrower than other parts, or multiple spacings can be set as variables and the optimal non-uniform spacing combination that achieves the target M value variation rate minimization can be determined through a simulation and optimization process.

[0064] The fundamental reason for adjusting the winding spacing non-uniformly in this way is to control the magnetic field distribution around the coil, thereby minimizing the variation range or variation rate (ΔM) of the M value even when a positional deviation occurs between the transmitting pad (100) and the receiving pad (200). Instead of intentionally slightly reducing the M value in the aligned state, the non-uniform spacing design mitigates the rapid decrease in the M value when a positional deviation occurs, ultimately reducing the difference in the M value between the aligned state and the maximum deviation state. This makes the system less sensitive to positional changes, thereby improving inverter control stability and providing relatively consistent charging performance even in various positions.

[0065]

[0066] The present inventors performed electromagnetic field simulations to quantitatively verify how effectively the coil winding spacing non-uniformity design (feature 1) described above can actually reduce the variation rate of the mutual inductance (M) value.

[0067]

[0068] [Simulation Conditions]

[0069]

[0070] * Model geometry: In the simulation, a DD coil geometry with a 3-turn or similar multi-turn structure was used as the transmit (Tx) coil and receive (Rx) coil model.

[0071] * Variable setting: For each of the transmit (Tx) coil and receive (Rx) coil, the gaps between adjacent turns were set as variables. For example, if there are three gaps, Tx_gap1, Tx_gap2, and Tx_gap3 were defined as independent design variables for the Tx coil, and Rx_gap1, Rx_gap2, and Rx_gap3 were defined as independent design variables for the Rx coil.

[0072] * Variable range: Each gap variable can have one of four values: 0 mm (no gap, close winding), 40 mm, 80 mm, and 120 mm. By combining these, a range from uniform gaps (all gaps = 0 mm) to various non-uniform gap structures can be implemented.

[0073] * Simulation Position Conditions: For each spacing combination, the mutual inductance (M) values ​​were calculated under the following two representative relative position conditions:

[0074] * Aligned: The state where the transmitting coil and the receiving coil are horizontally aligned and located at a reference vertical distance (e.g. X=0mm, Y=0mm, Z=100mm). The M value at this time is M alignment is defined as

[0075] * Maximum Misalignment: The maximum expected horizontal and vertical errors between the transmitting and receiving coils (e.g. X=75mm, Y=100mm, Z=150mm). The M value at this time is M deviation is defined as

[0076] * Evaluation Criteria: The performance of each interval combination was evaluated by calculating the M value fluctuation rate ΔM under the two location conditions mentioned above. The fluctuation rate is defined as follows:

[0077]

[0078] [Mathematical Formula 1]

[0079]

[0080]

[0081] [Simulation Results]

[0082]

[0083] We performed simulations for a large number of interval combinations (e.g., approximately 7680 valid combinations) and analyzed the results.

[0084]

[0085] * Reference (Uniform Spacing): When all spacing variables (Tx_gap1~3, Rx_gap1~3) were set to 0 mm to simulate a conventional uniformly spaced coil, the variation rate (ΔM) of the mutual inductance (M) value was calculated to be 34%. This result shows that the M value can vary by about 1 / 3 or more depending on the positional deviation.

[0086]

[0087] * The present invention (Non-uniform spacing - Minimizing Variation): By applying non-uniform spacing according to the present invention and optimizing to minimize ΔM, we were able to find a combination that significantly reduced ΔM values ​​by up to 6% in the best case. Exemplary spacing values ​​for this optimal combination were as follows:

[0088] * Tx gap (Tx_gap1, Tx_gap2, Tx_gap3): (120 mm, 120 mm, 40 mm)

[0089] * Rx gap (Rx_gap1, Rx_gap2, Rx_gap3): (0 mm, 80 mm, 40 mm)

[0090]

[0091] * The present invention (Non-uniform spacing - Considering target M values): When designing an actual system, it is important to consider not only the M value fluctuation rate, but also the absolute M value level required for power transmission. For example, optimization was performed by selecting the case with the lowest ΔM among combinations that satisfy a specific criterion M value or higher in both the on-position and maximum deviation states. As a result, an excellent combination with a ΔM value of 11% was derived. Example spacing values ​​in this case were as follows:

[0092] * Tx gap (Tx_gap1, Tx_gap2, Tx_gap3): (80 mm, 120 mm, 40 mm)

[0093] * Rx gap (Rx_gap1, Rx_gap2, Rx_gap3): (0 mm, 80 mm, 40 mm)

[0094]

[0095] [conclusion]

[0096]

[0097] The above simulation results clearly demonstrate that the proposed coil winding spacing non-uniform design can dramatically improve the variation rate of mutual inductance (M) values ​​due to positional deviations (e.g., from 34% to 6% or 11%) compared to conventional uniform-spacing designs. This supports the implementation of a robust and stable wireless power transfer system in response to positional variations through the present invention.

[0098]

[0099] Although the non-uniform spacing is explained using the winding section (112) of the transmitting pad (100) as an example in FIG. 2, this non-uniform winding spacing design can be applied equally or independently to the second winding section (114) as well as the receiving coil (210, see FIG. 1) included in the receiving pad (200). That is, only the transmitting coil can have a non-uniform spacing, only the receiving coil can have a non-uniform spacing, or both the transmitting coil and the receiving coil can be designed to have an optimized non-uniform spacing.

[0100]

[0101] Fig. 3 is a plan view showing in detail one specific example of a winding arrangement of a DD type coil (110) to which a non-uniform winding spacing design according to the present invention is applied. Fig. 3 illustrates a transmitting coil (110) including a first winding section (112), a second winding section (114), a third winding section (116), and a fourth winding section (118) arranged to form two D-shaped coil paths, and exemplifies that a non-uniformly adjustable spacing (G) is formed between the winding strands within each winding section.

[0102] FIG. 3 is a plan view showing in more detail a first embodiment of a coil (110) designed to minimize the variation rate of the mutual inductance (M) value by applying the principle of non-uniform winding spacing according to the present invention. This embodiment follows the DD type coil structure described in FIG. 2, and here the arrangement of the winding strands constituting the coil (110) is illustrated in detail. The illustrated coil (110) is designed to form two D-shaped current paths as a whole. For this purpose, for example, the coil area may be divided into four sections, such as a first winding section (112), a second winding section (114), a third winding section (116), and a fourth winding section (118), and the windings may be arranged therein. In the figure, two paths distinguished by different colors (e.g., blue and orange) each represent one D shape, and these two paths are arranged in a manner that intersects or interleaves each other in the central region of the coil to create the characteristic magnetic field distribution of the DD coil.

[0103] The non-uniformity of the winding spacing is achieved by intentionally setting the spacing (G) between adjacent winding strands within each winding section (112, 114, 116, 118) to be non-uniform in the structure of FIG. 3. As can be seen in FIG. 3, the spacing (G) is not the same in all areas. The winding spacing (G) in a portion crossing the center of the coil loop (e.g., the horizontally elongated winding portions in FIG. 3) may be set relatively wider than the winding spacing in an outer portion of the coil (e.g., the vertically oriented winding portions at the left and right edges in FIG. 3).

[0104] By adjusting the winding spacing non-uniformly in this way, by lowering the winding density in a specific area (e.g., the center) and increasing the density in other areas (e.g., the periphery), the spatial distribution and concentration of the magnetic field generated by the coil can be changed. This magnetic field distribution control alleviates the phenomenon in which the mutual inductance (M) value changes rapidly even when the relative positions between the transmitting coil (110) and the receiving coil (not shown) deviate somewhat from the ideal alignment state. That is, the non-uniform spacing (G) arrangement as shown in FIG. 3 lowers the sensitivity of the M value to positional deviation, which has the effect of significantly reducing the M value fluctuation rate (ΔM), as confirmed in the simulation results above. This ultimately contributes to improving the stability and performance consistency of the wireless power transfer system.

[0105]

[0106] Fig. 4 is a plan view showing an example of a winding arrangement of a second embodiment of a DD type coil (110) that applies a non-uniform winding spacing design according to the present invention, which is different from Fig. 3. Fig. 4 shows another arrangement structure of a transmitting coil (110) that forms two D-shaped coil paths, including a first winding section (112), a second winding section (114), a third winding section (116), and a fourth winding section (118), and here too, the spacing (G) between the winding strands can be intentionally set non-uniformly to reduce the M value fluctuation rate due to positional deviation.

[0107] As in the embodiment of FIG. 3, in the embodiment of FIG. 4, the spacing (G) between adjacent winding strands within each winding section may be intentionally set to be non-uniform to suppress fluctuations in the mutual inductance (M) value when a positional deviation occurs. For example, by differently adjusting the spacing (G) between the vertical winding sections passing through the central region of the coil and the spacing (G) between the horizontal winding sections in the peripheral region, the magnetic field distribution can be optimized, thereby achieving a stabilizing effect on the M value. Such non-uniform spacing settings can be applied by finding an optimal combination through simulations, etc.

[0108] Additionally, the winding arrangement structure illustrated in FIG. 4 can be implemented in combination with a multilayer winding structure in the coil edge region. Such a winding arrangement pattern can be applied in conjunction with a design in which at least some of the windings corresponding to the edge region of the coil (e.g., the outermost windings in FIG. 4) are stacked in a multilayer structure of two or more layers, particularly to maximize space efficiency. Such an edge multilayer structure can provide the following advantages. First, it is advantageous in securing a required inductance value or increasing the cross-sectional area of ​​the winding by increasing the total number of coil turns without increasing the overall planar area (footprint) of the coil pad, thereby reducing resistance. Second, the windings can be efficiently arranged within a limited space to secure the maximum 'coil window' size.

[0109] In conclusion, Fig. 4 can be said to show an example of a composite coil design method that pursues M-value stabilization through a non-uniform winding spacing design (feature 1) while simultaneously applying an edge multi-layer winding structure to further improve space efficiency and performance.

[0110]

[0111] In FIGS. 1 to 4, for the sake of convenience of explanation, the coil winding spacing non-uniformity has been mainly explained using the DD type coil structure as an example; however, the technical idea of ​​the present invention is not limited to a specific coil shape. This principle of optimizing the non-uniform winding spacing can be equally applied to coil structures of various geometric shapes capable of generating or receiving magnetic fields, such as circular, square, hexagonal, and elliptical. By appropriately designing the winding spacing pattern non-uniformly in consideration of the unique characteristics of each coil shape, it is possible to effectively reduce the rate of change in the mutual inductance (M) value due to positional deviation in the corresponding coil structure. In addition, the present invention can be applied not only to a single-phase wireless power transmission system using a single coil set, but also to a multi-phase system using multiple coil sets, thereby improving the stability and performance of the system.

[0112] In conclusion, the intentional non-uniform design of the coil turns' spacing proposed in the present invention brings the following major improvements to the wireless power transfer system. First, the variability of the mutual inductance (M) value is significantly reduced when positional deviation occurs, thereby stabilizing the electrical characteristics of the resonant circuit. This improves the control stability of the power conversion device (e.g., the inverter of the transmitter) and facilitates the design of the control algorithm. Second, it provides relatively consistent output power and charging speed even under various alignment error conditions, contributing to an improved user experience and higher average charging efficiency. Third, it reduces the need for complex feedback control loops or additional sensors that sensitively respond to and compensate for variations in the M value, simplifying the overall system structure and reducing related hardware and software development costs, as well as manufacturing costs.

[0113]

[0114] FIG. 5 is a plan view (top) and a side view (bottom) showing one embodiment of a hybrid magnetic core structure formed by combining different types of magnetic materials according to another aspect of the present invention. FIG. 5 illustrates that the hybrid magnetic core (120) is formed by a base magnetic body part (122) that forms a magnetic path in conjunction with a coil (110), and a second magnetic body part (124) that is selectively placed in a specific area on the base magnetic body part (122).

[0115] In a wireless power transmission system, the magnetic core (120) is a key component that forms a magnetic path together with the coil (110) and concentrates magnetic flux to increase energy transmission efficiency. Previously, ferrite was mainly used as a core material, but ferrite has limitations such as relatively low saturation magnetic flux density, low Curie temperature, and mechanical brittleness. On the other hand, amorphous or nanocrystalline magnetic alloys, which have recently been attracting attention, have advantages such as very high saturation magnetic flux density and magnetic permeability, excellent high-frequency loss characteristics, and temperature stability, but have the disadvantages of high material and processing costs and having to consider specific conditions (e.g., eddy current in a metal ribbon form, magnetic anisotropy of nanocrystalline).

[0116] The present invention proposes a hybrid magnetic core (120) structure that combines two or more types of magnetic materials with different characteristics, taking into account the advantages and disadvantages of each material, thereby optimizing both performance and cost efficiency.

[0117] In the embodiment illustrated in FIG. 5, the hybrid magnetic core (120) is largely composed of two parts. The first is a base magnetic body part (122) that forms the basic shape of the core and occupies a large area, and the second is a second magnetic body part (124) that is selectively placed only in a specific area on or inside the base magnetic body part (122).

[0118] * Base magnetic body portion (122): This portion maintains the overall shape of the core, supports the coil (110), and serves to provide a wide range of magnetic flux paths. Considering processability, cost, etc., materials such as ferrite or a relatively inexpensive amorphous magnetic alloy can be used. Ferrite has the advantage of being advantageous in suppressing high-frequency eddy current loss due to its high electrical resistivity.

[0119] * Second magnetic body portion (124): This portion plays a crucial role in improving the performance of the core. A high-performance magnetic material having a much higher magnetic permeability and / or a high saturation magnetic flux density than the base magnetic body portion (122) and at the same time very low core loss at high frequencies is used as the material. A nanocrystalline magnetic alloy can be a representative example. As can be seen in the plan view of Fig. 5, this high-performance second magnetic body portion (124) is not used throughout the entire core, but is strategically placed only partially in key paths (e.g., the area above the center of the coil) where the magnetic field is strongly concentrated by the coil (110) or where the main magnetic flux passes. This is to efficiently achieve the required performance improvement while minimizing the use of expensive high-performance materials.

[0120] An important design factor that must be considered here is the directionality related to the magnetic anisotropy of the material used as the second magnetic portion (124). In particular, high-performance nanocrystalline alloys manufactured through specific processes such as heat treatment in a magnetic field have the characteristic of being easily magnetized in a specific direction (magnetic easy axis). When using such anisotropic materials, the direction of the magnetic easy axis of the material must be arranged so that it is as much as possible aligned with the direction of the expected main magnetic flux flow within the core to maximize the material's inherent high permeability and low loss characteristics. If the magnetic easy axis and the magnetic flux direction are misaligned, the reluctance increases sharply and core loss and heat generation may actually worsen. Therefore, it is essential to accurately understand the characteristics of the material and to conduct precise arrangement that takes directionality into account.

[0121] Through this hybrid structure (122 + 124), each material creates a synergistic effect that complements each other's shortcomings and maximizes each other's advantages. That is, the base magnetic material (122) contributes to the basic structure formation and cost reduction, and the second magnetic material (124) provides low magnetic resistance in the core path to facilitate the magnetic flux flow, prevents the core from being easily saturated with its high saturation magnetic flux density characteristic, and significantly reduces heat generation with its low core loss characteristic. As a result, this hybrid magnetic core (120) structure exhibits excellent characteristics such as reduced overall magnetic resistance, reduced core loss and heat generation, and increased effective saturation magnetic flux density compared to a single material (especially a ferrite) core, thereby greatly contributing to achieving miniaturization, weight reduction, or high output and high efficiency in the same size of a wireless power transmission device.

[0122] In implementing such a hybrid structure, various configurations are possible by physically arranging and combining two or more types of magnetic material parts (e.g., 122, 124). The reason for providing various combination configurations is to secure flexibility in designing and implementing an optimal core structure by comprehensively considering the required performance of the target wireless power transmission system (e.g., efficiency optimization in a specific frequency band, strengthening magnetic flux concentration in a specific direction, heat suppression, etc.), the unique form of the magnetic material used (e.g., powder, block, ribbon, sheet, etc.) and processing characteristics, and the overall manufacturing cost.

[0123] Examples of specific combination configurations of hybrid magnetic cores that can be implemented according to the present invention are as follows, and these can be used alone or in combination with each other:

[0124] (1) Composition of different layers:

[0125] * This is a method of manufacturing the base magnetic body part (122) and the second magnetic body part (124) as separate layers and stacking them like rice cakes.

[0126] * The embodiment of FIG. 5 described above shows a structure in which a second magnetic body part (124) is partially stacked in a block shape on top of a base magnetic body part (122), and thus corresponds to the most representative example of such a ‘different layer configuration.’

[0127] * Other examples include a sandwich structure in which a second magnetic layer is inserted between base magnetic layers, or a multilayer thin film structure in which layers of various materials are sequentially stacked.

[0128] (2) Same Layer Configuration:

[0129] * This is a method of horizontally arranging the base magnetic body part (122) and the second magnetic body part (124) on the same plane or within a single layer.

[0130] * For example, the core plane can be divided into several regions, and a specific region (e.g., a central region with high magnetic flux density) can be filled with a second magnetic material (124) and the remaining regions can be filled with a base magnetic material (122) and attached side-by-side, or a part of the base magnetic material (122) can be hollowed out and a piece of the second magnetic material (124) can be inserted in that place, using an inlay method.

[0131] (3) Interleaved or Mixed configuration:

[0132] * This is a method of forming two or more types of magnetic materials into smaller units (e.g. thin ribbon strips, small blocks, powders, etc.) and then interleaving them or mixing them in a specific pattern or ratio to form a three-dimensional hybrid structure.

[0133] * For example, this may include periodically inserting high-permeability nanocrystalline sheets between ferrite core blocks to improve the overall permeability and saturation characteristics, or mixing magnetic powders with different characteristics and compression molding them to produce a core with desired composite characteristics.

[0134] As such, the present invention encompasses a variety of physical combinations and configurations that constitute a hybrid magnetic core. Designers can select or combine these various configuration options to optimally address the specific application requirements and manufacturing feasibility. This allows for more precise control and optimization of the core's overall effective permeability, loss characteristics, flux path, mechanical strength and durability, and heat dissipation characteristics.

[0135]

[0136] FIG. 6 is a perspective view showing the configuration of a wireless charging transmitting pad (100) and receiving pad (200) using magnetic cores (120a, 220a) optimized to have a width smaller than the width of each coil (110, 210) according to another aspect of the present invention. FIG. 6 illustrates an example in which a transmitting pad (100) including a transmitting coil (110) and a transmitting core (120a) of an optimized size positioned below it, and a receiving pad (200) including a receiving coil (210) and a receiving core (220a) of an optimized size positioned below (or above) it are arranged facing each other.

[0137] As illustrated, the size of the magnetic core (120a, 220a) is configured in an optimized ratio compared to the size (especially the width) of the corresponding coil (110, 210). Generally, the magnetic core is placed under (or above) the coil to form a magnetic path and concentrate magnetic flux, so it is often designed to cover the entire area occupied by the coil. However, as a result of research by the present inventors, it was found that the width of the magnetic core does not necessarily have to be equal to or larger than the width of the coil, and rather, under certain conditions, it may be more advantageous in terms of performance and economy to design the width of the core to be smaller than the coil.

[0138] The embodiment illustrated in FIG. 6 is based on this discovery. Looking at the transmitting pad (100), the width of the transmitting core (120a) positioned underneath it is formed narrower than the overall width of the transmitting coil (110). Similarly, in the receiving pad (200), it can be seen that the width of the receiving core (220a) is formed narrower than the width of the receiving coil (210). That is, FIG. 6 shows a specific example in which the core size is optimized to satisfy the relationship (core width) < (coil width).

[0139] In the simulation, for the same coil with a coil width of 470 mm, the mutual inductance (M) values ​​were compared under various position conditions when the magnetic core width was set to 470 mm, which is the same as the coil (reference comparison group), and when the core width was set to 370 mm, which is smaller (similar to 120a and 220a in FIG. 6, embodiment concept of the present invention). As a result, the case with a smaller core width of 370 mm showed a slightly higher M value overall in all evaluated position conditions (including alignment conditions and various deviation conditions). For example, under a specific alignment condition (e.g., Z=120 mm), the M value was measured to be 27.579 μH for the 470 mm core, but 28.106 μH for the 370 mm core. Under other alignment conditions (e.g., Z=190 mm) and deviation conditions, the M value of the 370 mm core was also higher. Although the rate of change of the M value itself did not differ significantly between the two cases, the absolute level of the M value improved.

[0140] These results suggest that optimizing the width of the magnetic core to be smaller than the coil width (as in 120a and 220a in Fig. 6) provides the following important advantages. First, it can obtain a higher mutual inductance (M) value, which can potentially improve the wireless power transfer efficiency or contribute to higher power transfer at the same efficiency. Second, it can physically reduce the amount of magnetic material required to manufacture the core, thereby reducing the weight of the core and simultaneously improving cost-effectiveness by reducing material and processing costs. It is expected that removing the core edge area will have the effect of increasing the efficiency of the main magnetic flux path or reducing losses such as eddy currents.

[0141] Therefore, when designing a magnetic core, it is suggested that the relative size ratio (especially width) to the coil size should be considered as an important optimization variable. Fig. 6 illustrates a specific embodiment in which, through such optimization, performance improvement and cost reduction can be achieved simultaneously by using a core (120a, 220a) with a narrower width than the coil (110, 210).

[0142]

[0143] FIG. 7 is a perspective view (top) and a side view (bottom) showing an example of a coil structure in which coil windings and connection wiring are integrated without a separate wiring layer according to the present invention, thereby optimizing the overall thickness. In particular, the dotted circles highlight areas in which the terminal processing of the coil windings and wiring for external connection are efficiently integrated within the structure.

[0144] In some existing structures, a separate wiring layer is placed between the coil layer and the magnetic layer to connect the coil terminals and external circuits. However, this increases the thickness of the overall pad. To address this issue, the present invention proposes a method for efficiently integrating the connection wiring within the coil layer without using a separate wiring layer.

[0145] The side view (bottom) of Figure 7 clearly demonstrates the thinness of the structure to which this feature 7 is applied. It consists solely of a magnetic core (upper gray layer) and a coil layer (lower multi-colored layer) containing all of the coil windings and their connecting wiring, resulting in a significantly thinner overall thickness compared to conventional multi-layer structures. This is because a separate "wiring layer" has been physically removed.

[0146] The perspective view (top) of Fig. 7 and the area highlighted with a dotted circle in both drawings show the portion where the start and end terminals of the coil winding are extended outward and connected. In this structure, the connection wiring is processed on the same plane as the coil winding or within the same layer. For example, the coil winding and the connection wiring pattern may be formed together on a single printed circuit board (PCB) layer, or the end portion of a Litz wire used as the winding may be processed so that it can be directly connected to a connector or terminal without additional wiring. As can be seen in the highlighted area of ​​Fig. 7, the connection wiring is efficiently arranged and extended along the corners or edges of the coil structure, enabling connection to an external circuit without occupying a separate vertical space.

[0147] By eliminating the separate layer for coil connection wiring and integrating the wiring within the coil layer, this approach has the direct effect of dramatically reducing the physical thickness of the wireless power transmission device. This increases device design flexibility and significantly enhances its applicability, particularly in thickness-sensitive applications such as vehicle-mounted devices and slim appliances. Furthermore, by reducing the number of layers, the manufacturing process can be simplified and associated costs reduced. Furthermore, through optimized wiring paths and fewer connection points, electrical performance (e.g., reduced resistance) and long-term reliability can be improved.

[0148]

[0149] Next, the electrical characteristics of each of the transmitting coil (e.g., 110) and receiving coil (e.g., 210), especially the self-inductance (L) value, are parameters that have a significant impact on the design and performance of the wireless power transfer system. In a system that uses a resonant method, the L value of the coil is not only a key factor in determining the resonant frequency, but is also closely related to the quality factor (Q-factor) and frequency response bandwidth of the circuit. In general, if other conditions are the same, the lower the L value, the wider the bandwidth of the resonant circuit tends to be. A wide bandwidth is advantageous in maintaining stable operation because it makes the system relatively insensitive to changes in impedance or output power even if the resonance point moves somewhat due to changes in the operating conditions of the system (e.g., distance between coils, alignment, ambient temperature, etc.).

[0150] However, the selection of the L value cannot be simply considered in terms of securing a wide bandwidth. The L value is not only directly related to the physical structure of the coil, such as the size, number of turns, and shape, but also has a complex trade-off relationship with various technical and economic factors such as the capacitance value of the capacitor required for resonance, the voltage / current level of the system, the specifications and cost of related components (switching elements, capacitors, etc.), and above all, the possibility of component mounting within a limited space. Therefore, when designing an actual system, a process is necessary to determine the optimal L value for each coil by comprehensively considering these factors.

[0151] Against this backdrop, the present invention proposes a method for setting the magnetic inductance values ​​of a transmitting coil and a receiving coil within a specific range, particularly from the viewpoint of securing system stability and optimizing mounting space and cost, and is described in detail below.

[0152]

[0153] First, it relates to optimizing the self-inductance value of a transmitting coil (e.g., 110 in Fig. 1) used in a transmitting device (e.g., 100 in Fig. 1) of a wireless power transmission system. According to a preferred embodiment of the present invention, the self-inductance LTx value of the transmitting coil is set to 100 uH or less.

[0154] One of the main reasons for setting the inductance value of the transmitting coil relatively low, below 100 uH, is to ensure stable power transmission by increasing the robustness against changes in resonance conditions that may occur during system operation. Wireless charging systems are generally designed so that the transmitting coil and resonant capacitor resonate at a specific frequency (e.g., 85 kHz). However, in actual operating environments, the resonance conditions may change slightly or significantly due to misalignment between the transmitting and receiving pads or changes in the electrical characteristics of components (coils, capacitors, etc.) due to system heat generation.

[0155] Theoretically, the lower the coil inductance, the wider the bandwidth of the resonant circuit's frequency response characteristics. A wider bandwidth means that even if the system's resonance point shifts somewhat, the system's impedance and resulting output power changes are relatively small. Therefore, designing the LTx value to a low value of 100 uH or less suppresses rapid output power fluctuations even when resonant conditions change, thereby ensuring the stable operation of power conversion devices such as inverters that control transmission power.

[0156] In addition, setting the LTx value to 100 uH or less is not simply a matter of considering technical effects, but also reflects realistic factors in terms of hardware implementation within the transmitter. For example, considering the flexibility in selecting components such as switching elements and capacitors used in the power conversion circuit (inverter) of the transmitter, the ease of component mounting in a limited space, and the manufacturing cost of the entire system, 100 uH or less can be determined to be a practical optimal range. For example, when the target resonant frequency is 85 kHz and LTx = 100 uH, a resonant capacitance of approximately 35 nF is required, which is a value that can be sufficiently implemented using currently commercially available standard capacitors.

[0157]

[0158] Next, it relates to optimizing the self-inductance value of a receiving coil (e.g., 210 in Fig. 1) used in a receiving device (e.g., 200 in Fig. 1) of a wireless power transmission system. According to a preferred embodiment of the present invention, the self-inductance LRx value of the receiving coil is set to 60 uH or less.

[0159] There are two main purposes for setting the inductance LRx value of the receiving coil relatively low, such as 60 uH or less. First, similar to the case of the transmitting coil, it is to maintain stable charging performance by minimizing fluctuations in the received power and final output power even when resonant conditions change (position deviation, heating, etc.). This is based on the same principle that a low LRx value broadens the bandwidth of the resonant circuit, thereby increasing its insensitivity to frequency changes. Second, and a particularly important consideration in the design of the receiving device, it is to minimize the physical space (volume or area) occupied by the resonant capacitor that forms the resonant circuit when connected in parallel or in series with the receiving coil (210). Since the receiving device is often mounted in places where space constraints are more severe than those of the transmitting device, such as electric vehicles or mobile devices, minimizing the component mounting space becomes a very important design goal. Although lower inductance (LRx) may require a relatively larger total capacitance (e.g., about 58 nF for LRx=60 uH at 85 kHz) to match the same resonant frequency, practical high-voltage / high-capacitance capacitor banks are often constructed by connecting multiple standard capacitor elements in series. By appropriately lowering the LRx value, the total number of series-connected elements required can be reduced (e.g., fewer capacitors may be needed on the Tx side), which can ultimately lead to savings in the mounting area or volume occupied by the capacitor bank, as well as in the cost of the components.

[0160] Therefore, setting the LRx value to 60 uH or less can be understood as a value that optimally considers the technical advantages (stability, capacitor space saving) described above, as well as the realistic constraints of limited internal space and component cost of the receiving device (current collector).

[0161]

[0162] The foregoing detailed description is not to be construed as limiting in any way and is to be considered illustrative. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are intended to be included within the scope of the present invention.

Claims

1. As a wireless power transmission device, a coil comprising a plurality of windings; and A magnetic core arranged to be magnetically coupled to the above coil Includes, A wireless power transmission device, characterized in that at least some of the gaps between the plurality of windings constituting the coil are set non-uniformly so as to reduce the rate of change in the mutual inductance value between the alignment state and the positional deviation state between the coil and the opposing coil.

2. In claim 1, The above non-uniform spacing is set so that the spacing between the windings located at the center of the coil is relatively wider than the spacing between the windings located at the outer part of the coil. A wireless power transmission device characterized by:

3. In claim 1, At least some of the windings in the edge region of the above coil are wound in a multilayer structure of two or more layers. A wireless power transmission device characterized by:

4. In claim 1, A wireless power transmission device characterized in that the rate of change of the mutual inductance (M) value is 15% or less as defined by the following mathematical expression 1: [Mathematical Formula 1] (However, Malignment is the mutual inductance value in a predefined alignment state, and Mdeviation is the mutual inductance value in a predefined maximum position deviation state.) 5. In claim 1, The above non-uniform gap is set to satisfy a preset minimum mutual inductance (M) value required for rated charging of the wireless power transmission device even in the state of the maximum position deviation. A wireless power transmission device characterized by:

6. In claim 1, The above coil is a DD coil shape. A wireless power transmission device characterized by:

7. In claim 1, The above coil is any one shape selected from the group of coil shapes: circular, square, hexagonal, or elliptical. A wireless power transmission device characterized by:

8. A wireless power transmission device according to claim 1, wherein the wireless power transmission device is a transmission device that transmits energy, and the magnetic inductance value of the coil is 100 uH or less.

9. A wireless power transmission device according to claim 1, wherein the wireless power transmission device is a receiving device that receives energy, and the magnetic inductance value of the coil is 60 uH or less.

10. In claim 1, the magnetic core, base magnetic portion; and Combined with the base magnetic body portion, comprising a second magnetic body portion having a different type of material than the base magnetic body portion and having a higher investment rate or higher saturation magnetic flux density characteristic, Hybrid magnetic core A wireless power transmission device characterized by:

11. In claim 10, The base magnetic body part and the second magnetic body part are arranged adjacent to each other within the same plane or layer or are arranged in a form in which one part is inserted within the other part. A wireless power transmission device characterized by:

12. In claim 10, The above base magnetic body part and the above second magnetic body part are arranged in a form in which they are separated into different layers and stacked in the vertical direction or the left-right direction. A wireless power transmission device characterized by:

13. In claim 10, The above base magnetic body part and the above second magnetic body part are processed into strip or block shapes, respectively, and are arranged alternately or mixed in a predetermined pattern to be arranged three-dimensionally. A wireless power transmission device characterized by:

14. In claim 1, The overall width of the magnetic core is formed to be smaller than the overall width of the coil, thereby improving the mutual inductance (M) value between the coil and the opposing coil. A wireless power transmission device characterized by:

15. In claim 1, The connecting wiring connecting the winding end of the coil and the external circuit is not formed in a separate wiring layer physically separated from the coil layer in which the coil winding is arranged, but is formed integrated with the coil winding within the coil layer, thereby reducing the overall thickness of the structure including the magnetic core and the coil layer. A wireless power transmission device characterized by:

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