Non-uniform transmitting coil for wireless power transmission
By using a transmitter coil designed with non-uniform winding density and a rectangular sub-coil array, the problems of uneven magnetic field distribution and poor anti-offset capability in drone wireless charging systems are solved, achieving efficient and stable drone charging.
Patent Information
- Application Number
- CN202511728390.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-24
- Publication Date
- 2026-02-27
AI Technical Summary
In existing wireless charging systems for drones, the traditional uniformly wound coils result in uneven magnetic field distribution, weak central magnetic field strength, and poor resistance to displacement, leading to low transmission efficiency.
The transmitting coil is designed with non-uniform winding density, with a denser central region and a sparser edge region. Combined with a 2×2 rectangular sub-coil array and magnetic core assembly, it forms a high-intensity magnetic field region, enhancing its anti-deflection capability.
It significantly improves the coupling stability and transmission efficiency of drone charging systems, and greatly enhances the anti-offset capability. It is suitable for consumer and industrial small and medium-sized drones, requires no complex control circuits, and has a simple process and low cost.
Smart Images
Figure CN121583729A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of wireless power transmission, and relates to a non-uniform transmitting coil for wireless charging of a UAV and a coupling mechanism comprising the same. Specifically, the present application relates to a non-uniform transmitting coil structure, aiming to improve the central magnetic field strength and improve the anti-offset capability. BACKGROUND
[0002] With the development of UAV technology, its application in the fields of power inspection, logistics distribution, agricultural plant protection, etc. is becoming increasingly widespread, but the lack of endurance has always been the core problem restricting the continuous operation of the UAV. Wireless power transmission technology (especially magnetic coupling resonance type) has become the mainstream solution for UAV charging due to its non-physical contact and high safety, and the structure design of the coil as the core component of the coupling mechanism in the wireless power transmission system determines the advantages and disadvantages of transmission efficiency and anti-offset capability.
[0003] At present, common transmitting coils mostly adopt single circular or rectangular coils and mainly use uniform winding methods. Such traditional coils have inherent magnetic field distribution defects due to the uniform winding method: firstly, the magnetic field generated by the coil is not uniformly distributed in space, and the magnetic field strength in the central region is relatively weakest. When the receiving coil is perfectly aligned, the coupling efficiency has not reached the optimum; secondly, when the receiving coil is horizontally offset relative to the transmitting coil, the coupling coefficient will sharply decrease, and the system transmission efficiency will significantly decrease, i.e., the anti-offset capability of the system is poor.
[0004] To improve the anti-offset capability of the coil, the existing technology proposes solutions such as multi-coil array switching and increasing the area of the transmitting coil. However, these solutions usually introduce complex control circuits, increasing the system complexity and cost. Another approach is to optimize the physical structure of the coil itself, but the current optimization mostly focuses on the topological structure and array arrangement method of the coil, and the research on fundamentally optimizing the magnetic field form by precisely controlling the spatial distribution of the winding density of the coil to simultaneously improve the central magnetic field strength and anti-offset capability is still insufficient.
[0005] Therefore, there is an urgent need in the art for a new structure of a transmitting coil that is simple in structure, does not require complex control, and can effectively improve the central magnetic field strength and significantly enhance the anti-offset capability of the system. SUMMARY
[0006] The present application aims to overcome the shortcomings of the prior art and provide a non-uniform transmitting coil and system. The coil strengthens the central magnetic field and widens the high-strength magnetic field region through a unique winding density distribution, thereby achieving simultaneous improvement of transmission efficiency and anti-offset capability under a simple structure.
[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: Firstly, the application provides a non-uniform transmitting coil for wireless power transmission, comprising a coil conductor composed of a plurality of sub-coils in series; wherein the overall winding density of the coil conductor is non-uniformly distributed, and the winding density of the central region is greater than that of the edge region.
[0008] Further, the plurality of sub-coils are four rectangular sub-coils arranged in a 2x2 matrix to form a planar array, and the spacing between adjacent sub-coils is 5mm; the four sub-coils are connected in series by wires.
[0009] Further, the winding density is embodied by the winding spacing; the central region adopts a first winding spacing D1, and the edge region adopts a second winding spacing D2, and D1<D2 is satisfied.
[0010] Further, the ratio of the second winding spacing D2 to the first winding spacing D1 is not less than 2.
[0011] Further, the first winding spacing D1 is 2mm, and the second winding spacing D2 is 6mm.
[0012] Further, the total number of turns of each rectangular sub-coil is the same.
[0013] Further, the total number of turns of each rectangular sub-coil is 11 turns, so that the self-inductance of the transmitting coil is adapted to the wireless power transmission operating frequency of 85kHz.
[0014] Further, it further comprises a magnetic core assembly, and the coil conductor is arranged on the magnetic core assembly; the magnetic permeability of the magnetic core assembly is 2300.
[0015] Further, the magnetic core assembly comprises a bottom plate and a side wall arranged around the edge of the bottom plate, thereby forming a groove structure for accommodating the coil conductor.
[0016] Secondly, the application provides a wireless power transmission system, comprising the transmitting coil as claimed in any one of the above, and a receiving coil; the shape of the receiving coil is a regular rectangular coil with a side length of 15cm, and the winding density of the receiving coil is uniformly distributed.
[0017] Further, the wireless power transmission system is applied to a UAV charging scene, and the total area of the transmitting coil is 20x20cm 2 , and the vertical air gap between the transmitting coil and the receiving coil is 2-5cm.
[0018] Compared with the prior art, the application has the following beneficial effects: 1. Coupling stability is significantly improved: through the non-uniform design of the transmitting coil (dense in the center and sparse at the edge), combined with the 2*2 sub-coil array, the coupling coefficient is 0.285 when directly opposite, the coupling coefficient remains 0.217 when the single-axis offset is 5cm, and the coupling coefficient is still 0.164 when the diagonal offset (X=Y) is 5cm, which is much higher than the existing uniform winding coil (k is usually <0.12 when offset is 5cm), effectively avoiding the interruption of charging caused by the landing offset of the unmanned aerial vehicle; 2. High transmission efficiency: the magnetic core assembly (PC40 material, permeability 2300) cooperates with the non-uniform winding coil to reduce magnetic field diffusion loss, and the system transmission efficiency is 80%-85% at a frequency of 85kHz and a gap of 3cm, which is higher than the existing non-magnetic core scheme (efficiency is usually <75%); 3. Strong scene adaptability: the transmitting coil area (20*20cm 2 ), the receiving coil size (15cm side length), and the air gap (2-5cm) are all designed for unmanned aerial vehicles, without the need to modify the landing gear structure of the unmanned aerial vehicle, and can be directly adapted to consumer and industrial small and medium-sized unmanned aerial vehicles; 4. Simple process and low cost: the sub-coil adopts a rectangular structure, which is easy to wind; the receiving coil is uniformly wound without complex process; the magnetic core assembly is a groove structure, which is easy to mass produce and suitable for industrial application. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 is a top view structural schematic diagram of the transmitting coil of the application.
[0020] Figure 2 is Figure 1 A-A sectional view, showing the accommodation relationship between the groove type magnetic core structure and the coil.
[0021] Figure 3 is a magnetic field distribution simulation comparison diagram of the coil of the application and the traditional uniform winding coil.
[0022] Figure 4 is a magnetic field strength comparison curve diagram of the coil of the application and the traditional uniform winding coil at different heights.
[0023] Figure 5 is a coupling coefficient comparison curve diagram of the coil of the application and the traditional uniform winding coil at different offset distances.
[0024] Explanation of figure marks: 1: coil conductor 11, 12, 13, 14: first, second, third, and fourth rectangular sub-coils 2: magnetic core assembly 21: bottom plate 22: side wall DETAILED DESCRIPTION The application will be further described in connection with the following specific examples, which are not intended to limit the scope of the application. 1. Coil conductor preparation: • The wire is selected to have a cross-sectional area of 0.5 mm 2 of multi-strand litz wire (to reduce skin effect loss at 85 kHz frequency); • Four rectangular sub-coils are made: each sub-coil has a side length of 10 cm (the total emission area of the four sub-coils arranged in a 2x2 matrix is 20x20 cm 2 ), and the number of turns is 11. When winding, the sub-coils near the center area are wound with a winding pitch of D1 = 2 mm, and the sub-coils near the edge area are wound with a winding pitch of D2 = 6 mm; • Sub-coil connection: the four sub-coils are arranged in a 2x2 matrix with a spacing of 5 mm between adjacent sub-coils, and are connected in series by litz wire to form a complete coil conductor; 2. Magnetic core assembly preparation: • The magnetic core material is PC40 manganese-zinc ferrite with a permeability of 2300; • The magnetic core assembly includes a bottom plate (size 20x20 cm, thickness 3 mm) and a side wall (height 1.5 cm, surrounding the edge of the bottom plate), forming a groove structure with a groove depth matching the thickness of the coil conductor (1.5 cm); 3. Assembly: • The coil conductor is embedded in the groove of the magnetic core assembly, ensuring that the coil conductor has no gap with the side wall of the magnetic core, and the preparation of the transmitting coil is completed. 4. Performance verification and effect • To verify the technical effect of the application, an analysis model is constructed using ANSYS Maxwell electromagnetic simulation software. The transmitting coil of the above-mentioned embodiment of the application is compared with a comparative example, which is a traditional rectangular array coil with the same total number of turns (44 turns) but uniformly wound (winding pitch of 4 mm). The simulation conditions are set as follows: working frequency 85 kHz, vertical air gap 3 cm, and receiving coil is a uniformly wound rectangular coil with a side length of 15 cm. • The simulation results are shown in Figure 3 、 Figure 4 、 Figure 5 . Figure 3 The magnetic field distribution cloud chart shows that the coil of the application forms a magnetic field with higher intensity and more uniform distribution in the central area. Figure 4 The curve shows that at different heights, the magnetic field intensity of the coil of the application is better than that of the comparative example coil. Figure 5The coupling coefficient-offset distance curve quantitative proof shows that in the single-axis (X direction) offset case, the coupling coefficient of the coil of the present application is significantly higher than that of the comparative coil in the whole offset range, especially when the offset distance reaches 5 cm, the coupling coefficient of the coil of the present application still remains at 0.217, while the coupling coefficient of the comparative coil has dropped to below 0.12; in the radial offset (X=Y) case, the coupling coefficient of the coil of the present application is higher than that of the comparative coil in the whole offset range, and when the X axis and the Y axis are both offset by 5 cm, the coupling coefficient of the coil of the present application reaches 0.164, which is higher than 0.119 of the comparative coil, fully proving the excellent anti-offset capability of the present application.
Claims
1. A non-uniform transmitting coil for wireless power transmission, characterized in that, Comprising: A coil conductor (1), which is composed of a plurality of sub-coils electrically connected in sequence by wires; wherein, the overall winding density of the coil conductor (1) is non-uniformly distributed, and the winding density in the central region is greater than that in the edge region.
2. The transmitting coil according to claim 1, characterized in that, The plurality of sub-coils are four rectangular sub-coils (11, 12, 13, 14), which are arranged in a 2×2 matrix form to form a planar array, and the gap between adjacent sub-coils is 5 mm; the four sub-coils are connected in series in sequence by wires.
3. The transmitting coil according to claim 1, characterized in that, The winding density is reflected by the winding pitch; the first winding pitch (D1) is adopted in the central region, and the second winding pitch (D2) is adopted in the edge region, and D1 < D2 is satisfied, and the ratio of the second winding pitch D2 to the first winding pitch D1 is greater than or equal to 2.
4. The transmitting coil according to claim 3, characterized in that, The first winding pitch D1 is 2 mm, and the second winding pitch D2 is 6 mm.
5. The transmitting coil according to claim 2, characterized in that, The total number of turns of each of the rectangular sub-coils (11, 12, 13, 14) is the same.
6. The transmitting coil according to claim 5, characterized in that, The total number of turns of each rectangular sub-coil is 11 turns, so that the self-inductance of the transmitting coil is configured to match the operating frequency of 85 kHz for wireless power transfer.
7. The transmitting coil according to any one of claims 1 to 6, characterized in that, It further includes a magnetic core component (2), and the coil conductor (1) is arranged on the magnetic core component (2); the magnetic permeability of the magnetic core component (2) is 2300, which is used to concentrate the magnetic field generated by the coil conductor (1).
8. The transmitting coil according to claim 7, characterized in that, The magnetic core component (2) includes a bottom flat plate (21) and side walls (22) arranged around the edge of the bottom flat plate (21), thereby forming a groove structure for accommodating the coil conductor (1).
9. A wireless power transmission system, characterized in that, Comprising the transmitting coil according to any one of claims 1 to 8, and a receiving coil; the shape of the receiving coil is rectangular, with both the length and width being 15 cm, and the winding density of the receiving coil is uniformly distributed.
10. The wireless power transmission system according to claim 9, characterized in that, The total area of the transmitting coil is 20×20cm. 2 The vertical air gap between the transmitting coil and the receiving coil is 2-5 cm.