Coupling Structure Against Horizontal and Rotational Offsets and UAV Wireless Charging System

Abstract

The present invention relates to the field of wireless charging technology, and specifically discloses a coupling structure and a drone wireless charging system that resist horizontal offset and rotational offset. The coupling structure includes a transmitting end and a receiving end, and is characterized in that: the energy transmitting coil of the transmitting end includes a plurality of solenoid coils, the plurality of solenoid coils are evenly distributed in a circle on the same plane, and the center lines of the plurality of solenoid coils intersect at the center origin position. The energy receiving coil of the receiving end includes a plurality of vertical plane coils, and the plurality of vertical plane coils are perpendicular to the plane where the energy transmitting coil is located and are also evenly distributed in a circle along the same height. The effects are: simple structure, convenient installation, especially suitable for the drone wireless charging system, not only having omnidirectionality, but also having excellent horizontal offset resistance and rotational offset resistance capabilities.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless charging, and particularly to a coupling structure resistant to horizontal and rotational offsets and a drone wireless charging system. Background Art

[0002] As a new type of navigation device, drones have now been widely used in many fields such as power line inspection, military patrol, aerial photography, and logistics distribution. Their flexibility and portability have continuously expanded their application fields, but at the same time, the limitation of battery life has gradually emerged, which greatly restricts their usage scope and scenarios. The traditional charging methods for drones are contact charging or battery swapping, but this obviously does not meet the requirements of unmanned and intelligent systems. At the same time, traditional contact charging also faces many problems such as poor environmental adaptability and plug wear.

[0003] To solve this pain point, wireless power transfer (WPT) provides a feasible solution. By configuring one or more wireless charging platforms in the application route of drones, this method greatly makes up for the problem of cruise distance caused by insufficient battery life of drones, and at the same time realizes unmanned and intelligent management. However, this solution also faces another problem. Especially in extreme weather and environmental conditions, it is very easy for drones to be parked on the charging platform with offsets or misalignments, resulting in low charging efficiency and unstable power transmission. Most of the existing wireless power transfer coupling mechanisms for drones do not have the ability to resist offsets. Although the mechanical centering structures of some drones can achieve precise alignment of drones, they greatly increase the complexity of the system. Therefore, it is very necessary to enhance the lateral and rotational offset tolerance of the coupling mechanism applicable to drones. The structures that have made breakthroughs in recent years also cannot face the dual challenges of rotation and horizontal offset at the same time. Summary of the Invention

[0004] In view of this, the present invention first provides a coupling structure resistant to horizontal and rotational offsets, and the technical problem to be solved is: how to enable the wireless charging system to have the capabilities of resisting horizontal and rotational offsets at the same time.

[0005] To achieve the above object, the specific technical solutions adopted by the present invention are as follows:

[0006] An anti-horizontal-offset and anti-rotation-offset coupling structure includes a transmitting end and a receiving end. The key lies in that: the energy transmitting coil of the transmitting end includes a plurality of solenoid coils, the plurality of solenoid coils are evenly distributed in a circle on the same plane, and the center lines of the plurality of solenoid coils intersect at the central origin position. The energy receiving coil of the receiving end includes a plurality of vertical plane coils, and the plurality of vertical plane coils are perpendicular to the plane where the energy transmitting coil is located and are also evenly distributed in a circle along the same height.

[0007] Optionally, the solenoid coil is a flat square solenoid coil, including a square magnetic core and a coil winding spirally wound on the square magnetic core.

[0008] Optionally, the inner ends of the plurality of solenoid coils are close to each other to enclose a polygonal blank area, and a longitudinal offset suppression coil is filled in the polygonal blank area.

[0009] Optionally, the longitudinal offset suppression coil includes a polygonal magnetic core located at the central origin position and a polygonal plane coil wound on the outer side surface of the polygonal magnetic core.

[0010] Optionally, the energy transmitting coil of the transmitting end includes eight solenoid coils, and the eight solenoid coils are evenly distributed in a circle on the same plane and are in a "rice" shape.

[0011] Optionally, the eight solenoid coils are connected in series with each other, and an energy transmitting circuit is also configured at the transmitting end.

[0012] Optionally, the inner ends of the eight solenoid coils are close to each other to enclose an octagonal blank area, and a longitudinal offset suppression coil is filled in the octagonal blank area. The longitudinal offset suppression coil includes an octagonal magnetic core located at the central origin position and an octagonal plane coil wound on the outer side surface of the octagonal magnetic core.

[0013] Optionally, the eight solenoid coils and the octagonal plane coil are all connected in series with each other, and an energy transmitting circuit is also configured at the transmitting end.

[0014] Optionally, the plurality of vertical plane coils are connected in series with each other, and an energy receiving circuit is configured at the receiving end.

[0015] Based on the above coupling structure, the present invention also provides a drone wireless charging system, which adopts the anti-horizontal-offset and anti-rotation-offset coupling structure described above. Among them, on the charging platform set at the transmitting end, the receiving end is set on the drone, and the energy receiving coil is set on the landing gear of the drone. This enables the drone to have the ability to resist both horizontal offset and rotation offset during the wireless charging process.

[0016] The remarkable effect of the present invention is:

[0017] The present invention provides a coupling structure that resists horizontal offset and rotational offset. The structure is simple and easy to install, and is particularly suitable for the wireless charging system of unmanned aerial vehicles. It not only has omnidirectionality, but also has excellent capabilities of resisting horizontal offset and rotational offset. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the "rice" - shaped coupling mechanism provided in Embodiment 1 of the present invention;

[0019] Figure 2 is a curve of the mutual inductance change of the "rice" - shaped coupling mechanism with horizontal offset provided in Embodiment 1 of the present invention;

[0020] Figure 3 is a curve of the mutual inductance change of the "rice" - shaped coupling mechanism with longitudinal offset provided in Embodiment 1 of the present invention;

[0021] Figure 4 is a schematic structural diagram of the coupling mechanism provided in Embodiment 2 of the present invention;

[0022] Figure 5 is a curve of the mutual inductance change of the coupling mechanism with horizontal offset provided in Embodiment 2 of the present invention;

[0023] Figure 6 is a curve of the mutual inductance change of the coupling mechanism with longitudinal offset provided in Embodiment 2 of the present invention;

[0024] Figure 7 is a curve of the mutual inductance change of the coupling mechanism with rotational misalignment provided in Embodiment 2 of the present invention;

[0025] Figure 8 is a schematic installation structure diagram of the wireless charging system of unmanned aerial vehicles provided in Embodiment 3 of the present invention;

[0026] Figure 9 is a schematic circuit diagram of the wireless charging system of unmanned aerial vehicles provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following specifically clarifies the implementation manners of the present invention in conjunction with the drawings. The given embodiments are only for illustrative purposes and should not be construed as limitations on the present invention. The drawings are only for reference and illustration, and do not constitute a limitation on the protection scope of the patent of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0028] Embodiment 1:

[0029] This embodiment provides a coupling structure that resists horizontal offset and rotational offset, as shown in Figure 1As shown, it includes a transmitting end and a receiving end. The energy transmitting coil of the transmitting end includes 8 solenoid coils. Of course, the number of solenoid coils can be appropriately adjusted according to the specific application scenario. In specific implementation, the solenoid coil is a flat square solenoid coil, including a square magnetic core and a coil winding spirally wound on the square magnetic core. The 8 solenoid coils are evenly distributed on the same plane according to the circumference and are in the shape of a "M", and the core lines of the 8 solenoid coils intersect at the center origin. The inner ends of the 8 solenoid coils are close to each other to enclose an octagonal blank area. The energy receiving coil of the receiving end includes two vertical plane coils, which are perpendicular to the plane where the energy transmitting coil is located and are distributed opposite to each other at the same height. Of course, the number of receiving coils can also be increased to 4 according to the application scenario, and can be evenly distributed in a circle opposite to each other.

[0030] In specific implementation, each solenoid coil is composed of 10 turns of coil winding wound on a 200×50×10mm ferrite core, and the energy receiving coil is designed as a rectangular coil with a size of 250×60×1.83mm, which is wound by 14 turns of coil. It is verified by experiments that when the above-mentioned coupling mechanism rotates 360° at the receiving end, the mutual inductance between the energy receiving coil and the energy transmitting coil changes very little, and it can be considered that it has omnidirectionality.

[0031] pass Figure 2 It can be seen that the structure can maintain a relatively stable mutual inductance value when there is a lateral offset (X-Misalignment) between the receiving coils. The mutual inductance and fluctuation rate are only 3.6% when the lateral offset is 5cm. However, the mutual inductance of the structure fluctuates greatly when there is a longitudinal offset (Y-Misalignment) between the energy receiving coils. When the offset reaches 5cm, the mutual inductance and fluctuation reach 28%. Figure 3 As shown, it can be seen that although the coupling structure for resisting horizontal and rotational deviation provided in this embodiment is omnidirectional, it cannot fully meet the requirement of resisting horizontal deviation, so it needs to be further optimized. In the figure, M12 represents the mutual inductance between the energy transmitting coil and a vertical plane coil, and M13 represents the mutual inductance between the energy transmitting coil and another vertical plane coil.

[0032] Embodiment 2:

[0033] To suppress the problem of large mutual inductance fluctuations under longitudinal offset in the coupling mechanism, this embodiment further optimizes on the basis of Embodiment 1. Considering that the middle free space of the energy emission coil in the coupling structure mentioned in Embodiment 1 has not been utilized, a coil can be added in the middle to suppress the mutual inductance fluctuations caused by the longitudinal offset of the receiving coil. As an implementation method, a common circular coil can be added in the middle. It can be seen from the simulation experiment results that it has a significant improvement effect on the mutual inductance fluctuations under longitudinal offset. In order to further improve its anti-offset performance and fully consider and utilize the octagonal area enclosed by the "cross" shape of the emission coil, this embodiment fills the octagonal blank area with a longitudinal offset suppression coil. Here, the longitudinal offset suppression coil includes a polygonal magnetic core located at the center origin position and an octagonal planar coil wound around the outer side of the polygonal magnetic core. In this example, the octagonal planar coil is wound with 10 turns, and the obtained coupling structure is as Figure 4 shown.

[0034] Performing a simulation experiment on it, the results are as Figures 5 - 7 shown, Figure 7 where M represents the total mutual inductance between the energy emission coil and the energy receiving coil. It can be seen that due to the existence of the symmetric structure of the energy emission coil in the coupling mechanism, the mutual inductance sum remains basically unchanged under rotation within 45°, that is, it can be known that the mutual inductance sum remains basically unchanged when the offset receiving coil rotates 360°, meeting the omnidirectionality. At the same time, when the energy receiving coil has a lateral offset and a longitudinal offset within 5 cm, the fluctuation of the mutual inductance sum does not exceed 5%. It can be determined that this structure has excellent anti-horizontal offset ability.

[0035] Embodiment 3:

[0036] Since the wireless charging coupling mechanism of the drone generally consists of two parts: an energy emission coil and an energy receiving coil. Among them, the energy receiving coil is installed on the drone, and its weight, volume, and installation position will all have a considerable impact on the specific performance of the drone. Currently, the common energy receiving coils are divided into three categories: planar coils, vertical planar coils, and solenoid coils. This embodiment selects the vertical planar coils as shown in Figure 1 and Figure 4 shown, which are installed on the landing gear of the drone and have the following advantages: (1) The air gap with the emission coil is small, which is beneficial to improving the transmission efficiency; (2) The coil is far from the fuselage, greatly reducing the electromagnetic interference of the magnetic field on the electronic devices inside the drone; (3) The coil is embedded in the landing gear, and it has strong adaptability to the drone structure.

[0037] Since the use of an embedded landing gear type energy receiving coil requires the energy transmitting coil to generate a horizontal magnetic field. In the past, circular or "double D" shaped energy transmitting coils were mostly used, but they do not have the ability to cope with horizontal offsets. It can be known from experiments that the anti-offset capabilities of planar coil coupling mechanisms, including circular coils and square coils, are very weak, which means that choices must be made outside the traditional planar coil field. The present invention selects a solenoid coil, and among them, the square solenoid coil is superior to the circular solenoid coil in terms of structural installation convenience and anti-offset ability. However, the conventional solenoid coil structure does not have an omnidirectional ability, which requires the energy transmitting coil to be a combined structure to meet various requirements such as omnidirectionality and anti-horizontal offset.

[0038] Combining the coupling structures for anti-horizontal offset and anti-rotation offset provided in Embodiment 1 and Embodiment 2, for the application scenario of UAV wireless charging, this embodiment provides a UAV wireless charging system, as Figure 8 shown. The coupling structure for anti-horizontal offset and anti-rotation offset described above is adopted. Among them, on the charging platform set at the transmitting end, the receiving end is set on the UAV, and the energy receiving coil is set on the landing gear of the UAV, so that the UAV can have the abilities of anti-horizontal offset and anti-rotation offset simultaneously during the wireless charging process.

[0039] Specifically in implementation, the eight solenoid coils can be connected in series with each other, or all eight solenoid coils and the octagonal planar coil can be connected in series with each other. In this way, the energy transmitting coil is actually equivalent to being composed of 8 solenoid transmitting coils and 1 octagonal transmitting coil. Usually, an energy transmitting circuit is also configured at the transmitting end. Similarly, multiple vertical planar coils are connected in series with each other, and an energy receiving circuit is configured at the receiving end. The system circuit structure is as Figure 9 shown. It can be seen that the wireless charging system circuit is composed of three parts: a voltage source inverter circuit, a compensation circuit, and a rectifier circuit. This system adopts a constant frequency working mode with a working frequency of 85 kHz. Cc, Cp, and Cs are the compensation capacitors of the compensation inductor (Lc), the transmitting coil (Lp), and the receiving coil (Ls) respectively. Their relationship can be expressed as:

[0040] C C =(ω 2 L C ) -1 C P =[ω 2 (L P -L T )] -1 C S =(ω 2 L S ) -1 (1)

[0041] Where ω is the working angular frequency of power transmission, satisfying ω = 2πf, and f is the working frequency, to meet the requirements of SAE J2954. Using the Fundamental Harmonic Approximation (FHA), the basic output voltage in phasor form can be expressed as:

[0042]

[0043] According to Kirchhoff's voltage law (KVL), using the relationship between the input and output voltages of the rectifier, we can obtain:

[0044]

[0045] Where U S is the root mean square (RMS) value, and:

[0046]

[0047] Substituting (1), (2), and (4) into (3), U L can be calculated as:

[0048]

[0049] It can be clearly seen from equation (5) that the output voltage U L on the load is independent of the load. On the contrary, it is determined by U dc , L T and M. Therefore, for the coupling mechanism provided by the present invention to resist horizontal and rotational offsets, as long as the mutual inductance value does not fluctuate too much during the offset process, the stability of the output voltage can be maintained. Combining with Figures 5 - 7 the simulation results shown, it can be seen that by using the coupling structure shown in Embodiment 2, all 360-degree rotational deviations and large-distance horizontal offsets can be tolerated, that is, the mutual inductance value fluctuates very little within the range of (-50mm, -50mm) ≤ (x, y) ≤ (50mm, 50mm), so as to meet the wireless charging requirements of unmanned aerial vehicles.

[0050] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A coupling structure against horizontal offset and rotational offset, comprising a transmitting end and a receiving end, characterized in that: The energy transmitting coil at the transmitting end includes a plurality of solenoid coils, the plurality of solenoid coils are evenly distributed in a circle on the same plane, and the center lines of the plurality of solenoid coils intersect at the center origin position. The energy receiving coil at the receiving end includes a plurality of vertical plane coils, and the plurality of vertical plane coils are perpendicular to the plane where the energy transmitting coil is located and are also evenly distributed in a circle along the same height; The solenoid coil is a flat square solenoid coil, including a square magnetic core and a coil winding helically wound on the square magnetic core; The inner ends of the plurality of solenoid coils approach each other to enclose a polygonal blank area, and a longitudinal offset suppression coil is filled in the polygonal blank area.

2. The coupling structure for resisting horizontal offset and rotational offset according to claim 1, characterized in that: The longitudinal offset suppression coil includes a polygonal magnetic core located at the center origin position and a polygonal planar coil wound on the outer side surface of the polygonal magnetic core.

3. The coupling structure against horizontal offset and rotational offset according to claim 1 or 2, characterized in that: The energy transmitting coil at the transmitting end includes eight solenoid coils, and the eight solenoid coils are evenly distributed in a circle on the same plane and form a "cross" shape.

4. The coupling structure against horizontal offset and rotational offset according to claim 3, characterized in that: The eight solenoid coils are connected in series with each other, and an energy transmitting circuit is also arranged at the transmitting end.

5. The coupling structure for resisting horizontal offset and rotational offset according to claim 3, wherein: The inner ends of the eight solenoid coils approach each other to enclose an octagonal blank area, and a longitudinal offset suppression coil is filled in the octagonal blank area. The longitudinal offset suppression coil includes an octagonal magnetic core located at the center origin position and an octagonal planar coil wound on the outer side surface of the octagonal magnetic core.

6. The coupling structure for resisting horizontal offset and rotational offset according to claim 5, wherein: The eight solenoid coils and the octagonal planar coil are all connected in series with each other, and an energy transmitting circuit is also arranged at the transmitting end.

7. The coupling structure for resisting horizontal offset and rotational offset according to any one of claims 4-6, characterized in that: The plurality of vertical plane coils are connected in series with each other, and an energy receiving circuit is arranged at the receiving end.

8. A wireless charging system for an unmanned aerial vehicle, characterized in that: Adopt the coupling structure for resisting horizontal offset and rotational offset according to any one of claims 1-7, wherein a charging platform is arranged at the transmitting end, the receiving end is arranged on an unmanned aerial vehicle, and the energy receiving coil is arranged on the landing gear of the unmanned aerial vehicle.

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