WO2016026095A1 - Thin high-efficiency wireless charging coil and wireless charging system thereof - Google Patents

Abstract

A thin high-efficiency wireless charging coil, comprising: a magnetic shielding piece (33); a winding (42) having a sectional wedge shape and comprising an inner edge (421), an outer edge (422), an outer edge platform (423) and an outer edge platform base (424), a thickness h₁ of the inner edge being less than a thickness h₂ of the outer edge, and a width d of the outer edge platform being less than a width D of the outer edge platform base; an accommodation space (43) formed by the inner edge together with the magnetic shielding piece pressing against the outer edge platform of the winding having a sectional wedge shape, the accommodation space being filled with magnetic powder; the inner edge is closest to the accommodation space and the outer edge is farthest away from the accommodation space, and the outer edge thickness and the inner edge thickness of the winding having a sectional wedge shape satisfy h₂ / h₁ ≥ 1.5. The wireless charging coil can achieve a greater product of a coupling coefficient and a system quality factor, K•Q, that is, better transmission efficiency, has a high space utilization and convenient wiring, and is more suitable for thinning requirements.

Description

 Thin high-efficiency wireless charging coil and wireless charging system thereof

 The present invention relates to the field of wireless charging, and more particularly to a thin high-efficiency charging coil and a wireless charging system using the same. technical background

 In recent years, with the development and popularization of electronic consumer products such as mobile phones, computers, and cameras, adapters for charging various electronic products have also developed into a huge industry. However, various adapters also cause inconvenience to people's lives, such as uncommon interfaces, inconvenient use of wires, generation of electronic waste, etc., and people are increasingly eager to charge various devices freely. Under the leadership of technology development, the idea of wireless power transmission has gradually become a reality and plays a vital part in our lives. For example, the American company Palm, which first applied wireless charging to mobile phones, introduced the "touch stone" to charge mobile phones with the principle of electromagnetic induction. China's Haier's conceptual "tailless TV" does not require power lines, signal lines and network cables. Japan's Fujitsu Corporation transmits magnetic resonance power, and the transmission distance can be as many as several meters.

There are several technologies for wireless charging: electromagnetic induction, electromagnetic resonance, radio wave, and electric field coupling. Among them, the electromagnetic induction method is a commercially successful wireless charging technology, as shown in Fig. 1, which is a circuit block diagram of the current electromagnetic induction mode. The transmitting coil Tx has an inductance L _s and an equivalent resistance R _s in series with the resonant capacitor C _s , and the receiving coil Rx has an inductance L _D and an equivalent resistance R _D in series with the resonant capacitor C _D . It can be seen that the distance between the transmitting coil Tx and the receiving coil Rx is D, and the two transmit energy through the coupled inductor M, and the design of the coil becomes critical. In engineering, the quality factor of the transmitting coil Tx is generally defined as Q _s =coL _s /R _s , and the quality factor of the receiving coil Rx is Q _D =coL _D /R _D , where ω=2πί· is the circular frequency.

The principle of electromagnetic induction realizes the wireless power supply. The resonant frequency is generally between 1 10~205ΚΗζ. If the magnetic radiation shielding is not good, it will bring potential safety hazards to the product. Because the charging coil is generally attached to the product, the battery and other conductive in the product. The body will absorb the electromagnetic energy from the transmitting coil Tx, and the temperature is long. The degree will gradually increase, which will burn the product and cause safety hazard to the human body. Therefore, in principle, the wireless charging scheme coil must be attached with a magnetic shield. The application of the magnetic isolation diaphragm can be said to be particularly important in the wireless charging scheme. It is not only for magnetic isolation to avoid radiation products, but also plays an important role in the overall efficiency of the entire product. The magnetic separators are usually placed on the bottom and top surfaces of the two coils, so that the electromagnetic energy is wrapped in the middle. , which in turn increases efficiency and lowers temperature. As shown in FIG. 2, the wireless charging coil is composed of a coiled coil Tx and a receiving coil Rx. The center of the transmitting coil Tx is provided with a positioning permanent magnet 22 to ensure that the receiving coil Rx can be aligned with the transmitting coil Tx. It is possible to effectively prevent the magnetic flux from being cut to the battery 21 behind the receiving coil Rx.

 The material of the magnetic isolation sheet 23 is mainly used for ferrite sheets, metal powder chips, amorphous laminates, etc. Basically, the properties of these materials have their own advantages, and the ferrite sheets have high magnetic permeability and low loss, and are shielded. The effect is better; the saturation magnetic flux density of the metal powder chip is higher; the amorphous lamination has better processability and can achieve a very thin lamination thickness. We know that the wireless charging coil is divided into a transmitting coil Tx and a receiving coil Rx. Since the transmitting coil Tx is often built in a separate wireless charging base, the thickness requirement is relatively low, so the current design and manufacture are relatively simple; The receiving coil Rx often needs to be built in the electronic device to be charged, such as a mobile phone, a camera, etc., so the thickness requirement is relatively high, and often requires a size of 1 mm or a thinner, so that the actual use will bring inefficiency and heat. Waiting for the situation.

At present, the prior art is insufficient in the thin design of the coil, and the top view and the flat view of the prior art receiving coil Rx are respectively illustrated in Figs. 3(1) and 3(2). As can be seen from the figure, because of the thinning, the receiving coil Rx uses two square wires and is wound around one layer. The problem is that such a winding causes a terminal 31 to fly from the inside of the coil winding 32 to the outside, so that the thickness of the entire receiving coil Rx is actually increased in addition to the thickness of the magnetic sheet 33 and the coil winding 32. The thickness of the one-layer outlet terminal 31 does not match the demand for thinning. In addition, for wireless charging applications, there is a free space between the transmitting coil Tx and the receiving coil Rx, which is open and has no magnetic conductive material. The magnetic flux in this space is large and the copper conductor is easily cut, so the receiving coil Rx adopts two squares. The practice of winding the wires will in fact bring about a large eddy current loss of the copper wire and reduce the efficiency of the transmission system. According to technical analysis, the power loss figure λ of the wireless charging coil defines the loss of the charging coil.

P _s and output power P. The ratio of _ut . The minimum power loss figure of merit λ _ιη is related to the product of the coupling coefficient Κ between the receiving coil Rx and the transmitting coil Tx and the system quality factor Q.

The system quality factor Q is the geometric mean of the transmitting coil Tx quality factor 3⁄4 and the receiving coil Rx quality factor Q _D .

We define the transmission efficiency of the charging coil as the output power P. The ratio of _ut to the input power Ρ _η , the maximum transmission efficiency can also be obtained by calculating the minimum power loss figure of merit λ „ _η .

A ^F QUt-1 It can be seen from the above analysis that the quality factor of the receiving coil Rx is much smaller than the quality factor Q _{s of the} transmitting coil Tx due to the thinning requirement of the receiving coil Rx, which becomes a bottleneck of the charging system. How to respond to the thinning requirements of the receiving coil Rx and effectively improve the K value of the charging coil to improve the efficiency η of the transmission system is a major challenge of the present invention. Summary of the invention

 The object of the present invention is to obtain a thin and high-efficiency charging coil. By reasonable magnetic circuit design and magnetic material selection and corresponding process cooperation, the present invention can obtain a higher coupling coefficient than the prior art under the condition of maintaining a thin size. The product K of the system and the quality factor of the system, that is, better transmission efficiency.

 In order to achieve the above object, the present invention discloses a thin high-efficiency wireless charging coil, which is characterized in that it comprises:

 a magnetic shield;

a wedge-shaped section winding, the wedge-shaped section winding including an inner edge, an outer edge, an outer edge platform, and An outer edge of the platform base, the thickness of the inner edge is smaller than the thickness h ₂ of the outer edge, and the width d of the outer edge platform is smaller than the width D of the outer edge platform base;

 An accommodating space, the magnetic isolation sheet is closely attached to the outer edge platform of the wedge-shaped winding, and is formed together with the inner edge, and the accommodating space is filled with magnetic powder glue;

 The inner edge is closest to the accommodating space, and the outer edge is farthest from the accommodating space, and the outer edge thickness and the inner edge thickness of the wedge-shaped cross-section winding satisfy:

h ₂ /hl . 5.

 Preferably, the present invention further comprises a thin high-efficiency wireless charging coil, characterized in that the relationship between the width D of the outer edge platform base of the wedge-shaped winding and the width d of the outer edge platform satisfies:

 Preferably, the present invention further includes a thin high-efficiency wireless charging coil, characterized in that the wedge-shaped cross-section winding is formed by winding a plurality of strands of Liesz wire.

 Preferably, the present invention further includes a thin high-efficiency wireless charging coil, wherein the magnetic isolation sheet is a planar magnetic spacer, and the magnetic spacer material comprises a magnetic permeability of 50 or more.

NiZn ferrite or MnZn ferrite.

 Preferably, the present invention further comprises a thin high-efficiency wireless charging coil, characterized in that the magnetic powder comprises an iron-based metal alloy powder and a resin colloid, and the magnetic permeability is greater than or equal to 5.

 Preferably, the present invention further includes a thin high-efficiency wireless charging coil characterized in that the iron-based metal alloy comprises FeSiAl, FeSi, FeSiCr, FeNi, FeNiMo.

 Preferably, the present invention further includes a thin high-efficiency wireless charging coil, characterized in that the outgoing lines of the wedge-shaped cross-section windings are external outgoing lines.

 Preferably, the present invention further includes a thin high-efficiency wireless charging coil, characterized in that the inner shape of the wedge-shaped winding includes a square or a circular shape.

 The invention also discloses a wireless charging system, characterized in that

The wireless charging system includes a transmitting coil and a receiving coil, at least one of which adopts a coil The thin high efficiency wireless charging coil of claim 1.

 Preferably, the present invention further includes a wireless charging system characterized in that

 The width of the largest outer edge platform base of the winding of the receiving coil of the wireless charging system is no greater than the width of the largest outer edge platform base of the winding of the transmitting coil.

 The thin high-efficiency wireless charging coil and the wireless charging system thereof having the above structure can obtain a product of a higher coupling coefficient and a system quality factor K.Q, that is, better transmission efficiency. Moreover, the space utilization rate of the scheme is high, the outlet is convenient, and it is more suitable for the thinning demand. DRAWINGS

 The above and other objects, features and advantages of the present invention will become apparent from the <RTIgt;

 Figure 1 is a block diagram of a circuit architecture for electromagnetic induction wireless charging;

 Figure 2 shows a schematic diagram of a wireless charging system;

 3(1) and 3(2) are a plan view and a plan view of a prior art receiving coil Rx; FIG. 4 is a cross-sectional view showing the high efficiency thin charging coil of the present invention;

 Figure 5 shows the magnetic flux distribution of the wireless charging system and the variation of the magnetic flux along the position of the receiving coil Rx;

 Figure 6 is a cross-sectional view showing the first preferred wedge-shaped winding 42;

 Figure 7 is a schematic view showing the dimensions of the embodiment shown in Figure 6;

 Figure 8 illustrates a schematic cross-sectional view of a second preferred wedge-shaped winding 42;

 Figure 9 illustrates a schematic cross-sectional view of a third preferred wedge-shaped winding 42. Table 1 is a comparison of the DC resistance of the receiving coil Rx and the reference receiving coil Rx and the AC resistance at 100 kHz and 200 kHz according to the present invention;

Table 2 compares the parameters of the transmission system and the reference transmission system of the present invention. Reference numeral 21 - battery

 22 permanent magnet

 23 magnetic separator

 31 one terminal

 32 coil winding

 33 magnetic separator

 41 magnetic separator

 42 wedge section winding

 421 a wedge-shaped winding inner edge

 422 a wedge-shaped winding outer edge

 423 a wedge-shaped winding outer edge platform

 424 - Wedge section winding outer edge platform base

 43—a housing space

 Please refer to the schematic diagram of the wireless charging system shown in Figure 2.

In order to increase the K value of the electromagnetic transmission system, the coupling inductance M of the transmitting coil Τχ and the receiving coil Rx can be increased, and the equivalent resistance R _D , R of both can be reduced without changing the system resonant circle frequency ω. _s to achieve, as shown below:

 As described above, it is a primary object of the present invention to provide a thin high efficiency wireless charging coil. Figure

5 shows the magnetic field line distribution of the wireless charging system composed of the transmitting coil Tx and the receiving coil Rx, and the magnetic flux Φ of the lower edge of the receiving coil Rx as a function of position.

It can be seen that there is a maximum magnetic flux Φ _Χ at the position of the magnetic flux generated by the transmitting coil Tx under the receiving coil Rx, where the magnetic field strength Η should also be 0, obviously, if we want this system to obtain the maximum coupling inductance In case of Μ, the position of the receiving coil Rx winding is preferably located just above the transmitting coil. Tx magnetic flux Φ _正 directly above. The actual situation is that, due to the demand for thinning of the coil, both coils are laid flat to a certain width of the coil, and the receiving coil Rx winding cannot be guaranteed to be just above the position of the opposite magnetic flux Φ. Moreover, if the receiving coil Rx winding is reduced in width so as to be just above the upper side of the H=0 position of the counterpart coil, the resistance R _D becomes larger due to the small width, and the difference in the coil width between the two leads to a lower coupling coefficient K. Increase the risk of eddy current loss and magnetic leakage of the winding. However, in order to obtain the maximum coupling inductance ,, we can make the receiving coil Rx winding arrange as many amps as possible at the position of the opposite magnetic flux Φ _Χ , that is, more turns; and arrange less in the distance away from the magnetic flux Φ Oh, that is, fewer turns. As can be seen from the figure, the position of the magnetic flux Φ of the transmitting coil 基本 is basically biased toward the outer edge 422 of the winding, which means that we need to have more turns on the outer edge 422 of the winding, and the inner edge of the winding 421 There are fewer turns, that is, a winding structure with a wedge-shaped cross section.

 Please refer to the schematic cross-sectional view of the high efficiency thin charging coil of the present invention shown in FIG.

 A wedge-shaped winding structure is applied.

 Specifically, the thin high-efficiency wireless charging coil of the present invention comprises the following components, a magnetic isolation sheet 41, a wedge-shaped cross-section winding 42 adhered to the center of the magnetic isolation sheet 41, and a magnetic spacer 41 and a wedge-shaped winding 42. Filled magnetic powder glue. The prepared wedge-shaped section winding 42 is adhered to the central position of the magnetic shield 41, and an accommodating space 43 is formed inside the two; the prepared magnetic powder is injected into the accommodating space 43 and heated and solidified to form high efficiency. Thin charging coil.

Returning to the circuit block diagram of the electromagnetic induction wireless charging system shown in FIG. 1, it can be known from the efficiency analysis of the foregoing wireless charging system that in order to obtain the maximum transmission efficiency, in addition to obtaining the maximum coupling inductance 尽量, we also need to obtain as much as possible. The low equivalent resistances R _D , R _s represent the losses of the thin high efficiency wireless charging coil of the present invention. The loss of the thin high-efficiency wireless charging coil includes the core loss of the magnetic material such as the magnetic spacer 41 and the eddy current loss of the wedge-shaped winding 42 by the magnetic flux.

Due to the thin high-efficiency wireless practical application environment of the present invention, the transmitting coil Tx and the receiving coil Rx are separated by a considerable distance, resulting in a small amount of excitation inductance of the entire transformer, so that under practical application conditions, the transformer transmission system is exchanged. The flux density swing ΔΒ is actually small. Under such conditions, the core loss of the magnetic material is actually dominated by the eddy current loss of the core. In the present invention, iron Both oxygen and magnetic powder have high electrical resistivity, so their eddy current loss is also small, then the equivalent resistance RD,

R _{s is} mainly determined by the eddy current loss of the coil winding being cut by magnetic lines of force.

 It is well known that a multi-strand Litz wire can effectively suppress eddy current losses in high frequency windings and is a good choice. We use a multi-strand Litz wire to prepare the wedge-shaped cross-section winding, in addition to reducing the copper wire eddy current loss to obtain a smaller equivalent resistance, and also based on the following process considerations: Multi-strand Litz wire has a certain plastic deformation Sex, which helps to obtain a higher copper window fill rate; also based on plastic deformation, in the case where the thickness of the inner winding 421 and the outer edge 422 of the coil winding are different, it helps us to obtain the possibility of exiting from the outside.

 As shown in Fig. 6, in the wedge-shaped winding inner diameter 421 and outer edge 422, the multi-strand Litz wire is naturally deformed into different shapes by the tension at the time of winding, thereby obtaining a good filling rate, and the two layers of coils are simultaneously from the inner edge. 421 is wound around the outer edge 422, and finally exits at the same time, avoiding the need to increase the thickness of the flying wire in the prior art. In actual manufacturing, the multi-strand Litz wire can be self-adhesive and heated and shaped after winding to facilitate assembly of the next one.

For the wedge-shaped winding 42 of the present invention, as shown in FIGS. 6-9, various implementations of the wedge-shaped winding of the present invention are given. The three different sectional windings each include an inner edge 421 and an outer edge 422. an outer edge of the platform 423 and the outer edge of a base platform 424, 421 within the thickness of the outer edge 422 is less than 1 ^ thickness h _2, the width d of the outer edge of the platform 423 is less than the width of the outer edge of the platform base d 424, and 421 along the inner Near the accommodating space 43, the outer edge 422 is the farthest from the accommodating space 43. I, the ratio of the thickness of the outer edge 422 to the thickness of the inner edge 421 / ^ should not be less than 1.5, the ratio of the outer edge 422 thickness h ₂ to the thickness of the inner edge 421 is not less than 1.5. Preferably, it should be not less than 2. From the perspective of efficiency, in order to obtain the largest possible coupling inductance M, we hope that the number of turns of the outer edge 422 is as much as possible, so the ratio d/D of the width D of the outer edge platform 424 to the width d of the winding base should be not less than 10%. Should be no less than 20%.

The magnetic separator of the prior art often uses ferrite sheets, metal powder chips, amorphous laminates and the like. Among them, the metal powder chips are limited in size and process, and the magnetic permeability can only be about 20 to 30, resulting in Under the same coil and number of turns, the inductance of the receiving coil Rx is small, and the result is that the quality factor is small; and the metal lamination represented by the amorphous lamination is used as the magnetic spacer, although the processability is good, And have one The flexibility is fixed, but the electrical conductivity of the metal lamination is large. In the case of the existing transmission system frequency of about 110 kHz to 205 kHz, eddy current loss is easily generated, although the magnetic radiation can be suppressed from being transmitted to other conductors such as batteries in the product. Etc. However, the eddy current loss will inevitably lead to a small quality factor; while the ferrite sheet has a relatively high magnetic permeability, and due to its oxide ceramic structure, the electrical conductivity is low, and eddy current loss is not easily generated, but the saturation magnetic field of the ferrite The pass density is lower than the first two materials.

 For the purpose of the present invention, in order to obtain higher transmission efficiency, the material of the thin magnetic high-efficiency wireless charging coil of the present invention is selected from ferrite, that is, including manganese zinc, nickel zinc ferrite, according to the foregoing. Analysis shows that the ferrite has a high magnetic permeability and a large resistivity, and it is easy to obtain a high quality factor Q. Of course, for this purpose, we define the permeability of the ferrite to be 50 or more, and the preferred magnetic permeability is greater than or equal to 100. The thin high-efficiency wireless charging coil of the present invention obtained at this time has a high sensitivity. The problem of small ferrite saturation flux density can be compensated by reasonable magnetic circuit structure arrangement, that is, in the wedge-shaped winding inner edge 421, the coil thickness is thin, and the magnetic material is thick; in the wedge-shaped winding The outer edge 422 has a thicker coil and a thinner magnetic material.

 Finally, the wedge-shaped section winding 42 is adhered to the center of the magnetic isolation sheet 41, and an accommodating space 43 is formed. To effectively increase the magnetic permeability of the accommodating space 43, we fill the space with magnetic powder, the magnetic powder. The magnetic permeability of the rubber is greater than or equal to 5, and preferably its magnetic permeability is 10 or more to ensure an increase in the inductance of the thin high-efficiency wireless charging coil of the present invention.

 In order to prevent saturation of the filling portion, the magnetic powder is composed of a mixture of an iron-based metal alloy powder having a high saturation magnetic flux density and a resin colloid such as FeSiAl, FeSi, FeSiCr, FeNi, FeNiMo or the like. The filling of the magnetic powder glue not only helps to increase the inductance, but also improves the magnetic saturation condition near the inner edge 421 of the winding, and the solidification of the winding and the magnetic isolation sheet 41 after the colloid is solidified, so that the entire thin high-efficiency wireless charging coil of the present invention is obtained. More solid and not fragile.

 At this time, the thin high-efficiency wireless charging coil of the present invention is completed, and the present invention can obtain a product K of a higher coupling coefficient and a system quality factor with respect to the prior art, that is, better transmission efficiency. The solution has high space utilization rate and convenient outlet, which is more suitable for thinning requirements.

It should be noted that the thin high-efficiency wireless charging coil wedge-shaped winding inner edge 421 of the present invention may have a square or circular shape, which does not affect the technical details described above. Using the thin type of the invention A high efficiency wireless charging coil is only used as the receiving coil Rx, or only as the transmitting coil Tx, or both, to form a charging system, and is also within the scope of the present invention. Of course, using the wireless charging system of the thin high-efficiency wireless charging coil of the present invention, in order to obtain the maximum coupling inductance, we hope that the maximum outer edge width of the winding of the receiving coil Rx is not greater than the maximum outer edge width of the winding of the transmitting coil Tx. Revealed in Figure 5.

 Fig. 8 is a schematic cross-sectional view showing the wedge-shaped section winding 42 in the second preferred embodiment, which is shown by pre-forming each of the Litz wire to a predetermined shape.

 Fig. 9 is a schematic cross-sectional view showing the wedge-shaped winding 42 in the third preferred embodiment, showing that the inner edge 421 is a layer winding and the outer edge 422 is a two-layer winding. The technology of the present invention can be explained in detail in the following embodiments. Example 1

The outer edge of the wedge-shaped winding 421 has a diameter of 15 and the thickness of the inner edge 421 is 0. 3 mm, the thickness of the outer edge 422 is h. ₂毫米为0. 7mm, the winding base width D is 10. 5mm, the outer edge platform 424 width D is 2. 8mm ₀ The multi-strand Litz wire is made of self-adhesive wire, starting from the inner edge 421 from the inside to the outside For the two-layer winding, due to the deformation of the tension, it is slowly extruded into a wedge-shaped winding in the mold. After the winding of the wedge-shaped cross-section winding is completed by hot air baking, the two outlet terminals are wound out at the outer edge 422 of the winding. The baked winding is fixed at an intermediate position of the magnetic isolation sheet 41 having a size of 44 mm*40 mm*0. 4 mm. The magnetic isolation sheet 41 is made of NiZn and has a magnetic permeability of 120. The magnetic shield 41 is self-adhesive and helps to fix the wedge-shaped winding 42 at the center of the magnetic shield 41. A FeSiCr powder having an average particle diameter of about 5 μm was mixed with an epoxy resin to prepare a magnetic powder having a magnetic permeability of 12. The magnetic powder glue has fluidity, and the magnetic powder glue is injected into the accommodating space 43 formed between the magnetic isolation sheet 41 and the wedge-shaped cross-section winding, and after being leveled, the whole is placed in an oven to be baked and solidified, and the wireless charging reception is completed. Coil Rxl.

The other reference receiving coil Rx2 has a size of 44 mm*40 mm*0. 4 mm, and the winding adopts a square wire of 0.23 mm and is wound around 15 Ts, and the winding width is 10 mm, wherein the column diameter is 15 mm. Since the winding is only one layer, one terminal needs to fly out from the inner edge 421, increasing the thickness of the entire winding. 2毫米以下。 The reference thickness of the present invention is controlled to 1. 2mm or less.

 As shown in Table 1, it is a comparison of the DC resistance of the receiving coil Rx1 of the present invention and the reference receiving coil Rx2 and the AC resistance at 100 kHz and 200 kHz. It can be seen from the figure that the eddy current loss of the Rx2 square copper wire coil after being cut by the magnetic force line is large, and the corresponding 100KHz, 200KHz AC resistance is much larger than its DC resistance, and the multi-strand Litz wire is used for receiving. The coil Rxl can effectively suppress the eddy current loss of the copper wire, and the difference between the alternating current resistance and the direct current resistance is not large.

表 1

Table 1

 Example 2

A transmitting coil Tx, the winding is wound by two layers of 105 strands of 0.05 mm multi-strand Litz wire, each layer is wound 10Ts, a total of 20Ts. 5毫米*43mm*2. lmm。 The winding size is 20. 5mm * 43mm * 2. lmm. The magnetic isolation piece 41 has a size of 53 for *53 mm*3 mm, and the material is made of manganese-zinc power ferrite PC44, and the magnetic permeability is about 2000 u. The coil is bonded to the center of the magnetic shield 41, that is, the transmitting coil Tx is formed. 5毫米的组成形成组成。 The transmission coil Τχ is respectively symmetrical with the center of the receiving coil Rx1 and the reference receiving coil Rx2 of the present invention, and the pitch is set to 4. 5mm, constitute a transmission system. To assist in aligning the transmitting coil Tx with the receiving coil Rx, a positioning magnet can be provided at the center of the transmitting coil Tx. As shown in Table 2, the parameters of the transmission system and the reference transmission system of the present invention are compared, and the parameters of the two transmission systems are respectively at the OOKHz and 200KHz frequencies. It can be clearly seen that the transmission system using the receiving coil Rx1 of the present invention has a coupling inductance M which is 11% higher than that of the reference transmission system, indicating that the wedge-shaped winding has a higher coupling inductance even under the same thickness condition. Whether it is l OOKHz or 200KHz, it can be determined that the multi-strand Litz wire has a smaller eddy current loss, that is, a smaller equivalent resistance R _D . Since the coupled inductor M is larger, the equivalent resistance R _D is smaller, meaning that the receiving coil Rx of the present invention has a higher KQ value. It can be seen that the invention of the present invention can effectively improve the efficiency of the transmission system while maintaining the requirement of a thin size as compared with the prior art.

表 2

Table 2

 The previous description of the preferred embodiments is provided to enable any person skilled in the art to use or utilize the invention. Various modifications to these embodiments are obvious to those skilled in the art, and the general principles described herein may be applied to other embodiments without the use of inventive. Thus, the present invention is not intended to be limited to the embodiments shown,

Claims

Claim A thin high-efficiency wireless charging coil, comprising:  a magnetic shield; a wedge-shaped section winding, the wedge-shaped section winding includes an inner edge, an outer edge, an outer edge platform and an outer edge platform base, the inner edge has a thickness smaller than a thickness h _{2 of} the outer edge, the outer The width d along the platform is smaller than the width D of the outer edge platform base;  An accommodating space, the magnetic isolation sheet is closely attached to the outer edge platform of the wedge-shaped winding, and is formed together with the inner edge, and the accommodating space is filled with magnetic powder glue;  The inner edge is closest to the accommodating space, and the outer edge is farthest from the accommodating space, and the outer edge thickness and the inner edge thickness of the wedge-shaped cross-section winding satisfy: h ₂ /hl . 5. 2. The thin high efficiency wireless charging coil according to claim 1, wherein  The relationship between the width D of the outer edge platform base of the wedge-shaped winding and the width d of the outer edge platform satisfies:  d/D^ 10 The thin high-efficiency wireless charging coil according to claim 1 or 2, wherein the wedge-shaped cross-section winding is formed by winding a plurality of strands of Liesz wire. 4. The thin high efficiency wireless charging coil according to claim 3, wherein  The magnetic isolation sheet is a planar magnetic isolation sheet, and the magnetic separation material comprises a magnetic permeability of 50 or more. NiZn ferrite or MnZn ferrite. The thin high-efficiency wireless charging coil according to claim 3, wherein the magnetic powder comprises an iron-based metal alloy powder and a resin colloid, and the magnetic permeability is greater than At 5.  The thin high-efficiency wireless charging coil according to claim 5, wherein the iron-based metal alloy comprises FeSiAl, FeSi, FeSiCr, FeNi, FeNiMo.  7. The thin high efficiency wireless charging coil according to claim 5, wherein  The outgoing lines of the wedge-shaped windings are all external outgoing lines. 8. The thin high efficiency wireless charging coil according to claim 7, wherein  The inner shape of the wedge-shaped winding includes a square shape or a circular shape. A wireless charging system, characterized in that  The wireless charging system includes a transmitting coil and a receiving coil, at least one of which uses the thin high efficiency wireless charging coil of claim 1. 10. The wireless charging system of claim 9 wherein:  The width of the largest outer edge platform base of the winding of the receiving coil of the wireless charging system is no greater than the width of the largest outer edge platform base of the winding of the transmitting coil.