Adjustable inductance coil and control method

Abstract

The present invention relates to the field of electronic products, and in particular to an adjustable inductance coil and a control method. The adjustable inductance coil comprises a mechanical expansion and contraction mechanism and an inductance coil group, wherein a plurality of connection points are provided on the mechanical expansion and contraction mechanism, the inductance coil group being fixed on the connection points. During the process of expansion and contraction of the mechanical expansion and contraction mechanism, the distance between adjacent connection points changes, such that the inductance coil group neither generates excessive tension nor sags. The present invention relates to a mechanically-manipulated deformable coreless coil structure, which may be used as a power resonant device or a transmitting or receiving coil for wireless energy transmission. The inductance value of the coil may be changed by means of an electric motor or a manual operation. When the coil cooperates with the electric motor, the inductance of the coil can be accurately measured and controlled by a sensor and a control circuit, or is directly controlled by means of cooperation with a power electronic driver to obtain the optimal operating conditions. The present invention achieves a high compression ratio in terms of structure, such that a large-sized coil can be accommodated by a very small size.

Description

Adjustable inductor coil and control method TECHNICAL FIELD

[0001] The present application relates to the field of electronic products, in particular to an adjustable inductor coil and a control method. BACKGROUND

[0002] The existing inductor devices, or coils for wireless power transmission, are generally designed with fixed inductance values. There are also adjustable inductors, usually by changing the position of the magnetic core or the air gap. However, these adjustable inductor devices usually have limited power handling range and are only suitable for signal circuit applications. Magnetic devices in power scenarios usually need to be optimized for application to reduce magnetic loss and copper loss, and are not suitable for making inductors with large variable values.

[0003] In wireless power transmission applications, the inductance value of the coil as a transmitting and receiving element, together with the compensation capacitor, determines the resonance frequency. Due to component errors, wireless power transmission systems produced in large quantities usually cannot all work at the optimal frequency. In some applications, if the inductance value of the transmitting coil can be changed to adjust the resonance frequency, the optimal efficiency operating frequency point can be found under misalignment conditions. In some applications, the operating frequency of wireless power transmission must be fixed. Manually adjusting the inductance or capacitance of the transmitting coil is time-consuming and laborious, and cannot be adjusted in real time in applications.

[0004] In long-distance wireless power transmission systems, in order to improve transmission efficiency, large-size transmitting and receiving coils are usually required, which are not convenient for mobile applications. If the coil can be stored in a small size and only expanded when in use, it can be conveniently applied.

[0005] Patent US10806352B2 has a variable inductance structure by changing it, but it is used as an implanted passive device, which changes the inductance value and resonance point by blood vessel deformation, and cannot be used as an active adjustable inductor. SUMMARY

[0006] To solve the above problems, the present application provides an adjustable inductor coil, characterized in that it comprises a mechanical expansion and contraction mechanism and an inductor coil group. The mechanical expansion and contraction mechanism has multiple connection points, and the inductor coil group is fixed on the connection points. During the expansion and contraction of the mechanical expansion and contraction mechanism, the distance between adjacent connection points changes, so that the inductor coil group does not produce excessive tension and does not hang.

[0007] Further, the mechanical expansion and contraction mechanism comprises a screw rod, an upper central component, a lower central component, and an even number of more than six scissor arms, wherein the upper central component and the lower central component are movably mounted on the screw rod and can relatively approach or move away along the axial direction of the screw rod, the scissor arms are arranged in a central symmetric form around the upper central component and the lower central component, and the upper end point and the lower end point of each scissor arm are movably connected to the upper central component and the lower central component respectively; the upper end point of the odd-numbered scissor arm and the lower end point of the even-numbered scissor arm are connected to the inductor coil group as connecting points.

[0008] Further, a motor is connected to the screw rod, the lower central component is mounted on the screw rod through a bearing, and the upper central component is mounted on the screw rod through thread engagement, so that when the screw rod rotates with the motor, the lower central component does not move up and down along the screw rod, and the upper central component moves up and down along the screw rod.

[0009] Further, a plurality of sliding guide rails are arranged through the upper central component and the lower central component, so that the planes of the upper central component and the lower central component always remain parallel.

[0010] Further, the length of a single connecting rod of the scissor arm is determined by the following formula:

[0011] wherein L s represents the length of a single connecting rod of the scissor arm 102;

[0012] R o represents the radius of the circumscribed circle of the regular polygon when the inductor coil group is fully expanded;

[0013] N s represents the number of sides of the regular polygon when the inductor coil group is fully expanded.

[0014] Further, the number of scissor arms is determined by the following formula:

[0015] wherein N stage represents the number of scissor arms;

[0016] The upper central component and the lower central component are circular, and the radius thereof is determined by the following formula:

[0017] wherein R 补 represents the radius of the upper central component and the lower central component.

[0018] Further, the number of scissor arms is 14, 20, 26, or 32.

[0019] The application further provides an inductance control method based on the adjustable inductance coil, and the method further comprises a voltage and current sensor and a negative feedback controller, and the method comprises the following steps: obtaining the waveforms of voltage and current by using the voltage and current sensor, so as to obtain the current inductance value of the adjustable inductance coil at this time; obtaining the difference value by comparing the current inductance value with a target inductance value; and adjusting the motor according to the difference value by using the negative feedback controller, so that the inductance value of the adjustable inductance coil reaches the target inductance value; and adjusting the motor according to the amplitude of the measured current value or the phase of the voltage by using the negative feedback controller, so that the current reaches the target amplitude or phase.

[0020] The application further provides an adjustable inductance coil, and the mechanical expansion and contraction mechanism comprises N basic scissor structures and a central operating mechanism, wherein the basic scissor structure comprises two peripheral basic components, the peripheral basic component is composed of two connecting rods with equal lengths, the two connecting rods are fixedly connected at the tail end, the included angle between the two connecting rods is θ, and the length of the connecting rod is L0; the two peripheral basic components of each basic scissor structure are overlapped at the central end point and are connected through a rotating shaft; the N basic scissor structures are connected through rotating shafts at the tail end to form inner and outer regular polygons, and N is a natural number greater than 2; wherein the relationship between N and θ is as follows:

[0021] Each end point of the outer polygon is connected with the inductance coil group as a connecting point; the operating connecting rod with a length of L1 is fixed on the angle bisector of the upper and lower peripheral basic components of more than one basic scissor structure; wherein the calculation formula of L1 is as follows:

[0022] The central operating mechanism comprises an upper layer and a lower layer, which are an upper operating mechanism and a lower operating mechanism, wherein the upper operating mechanism and the lower operating mechanism are connected through a rotating shaft, and the rotating shaft is arranged at the central point of the inner and outer regular polygons formed by the N basic scissor structures; the upper operating mechanism and the upper operating connecting rod are connected in the mode of the rotating shaft, and the lower operating mechanism and the lower operating connecting rod are connected in the mode of the rotating shaft. Advantageous effects:

[0023] The application is a mechanically-operated deformable coreless coil structure, which can be used as a power resonant device or a transmitting or receiving coil for wireless energy transmission. The inductance value of the coil can be changed by a motor or manual operation. When the coil is matched with a motor, the inductance value of the coil can be accurately measured and controlled by a sensor and a control loop, or the coil can be directly matched with a power electronic driver for control to obtain the best working condition. In the structure, the application realizes a high compression ratio, and a large-size coil can be stored in a very small volume. BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1 is a vertical folding structure diagram of the embodiment of the application;

[0025] Figure 2 is a diagram of the vertical folding structure in the embodiment of the present application;

[0026] Figure 3 is a diagram of the side view of the vertical folding arm in the embodiment of the present application in the folding process;

[0027] Figure 4 is a diagram of the end point trajectory of the mechanism in the embodiment of the present application;

[0028] Figure 5 is a diagram of the distance change between adjacent connection points in the embodiment of the present application;

[0029] Figure 6 is a diagram of the relationship between the number of edges and the error in the embodiment of the present application;

[0030] Figure 7 is a diagram of the inductance change in the embodiment of the present application;

[0031] Figure 8 is a diagram of the planar folding structure in the embodiment of the present application;

[0032] Figure 9 is a diagram of the planar folding structure in the embodiment of the present application;

[0033] Figure 10 is a diagram of the planar folding structure in the embodiment of the present application;

[0034] Figure 11 is a diagram of the peripheral base structure in the embodiment of the present application;

[0035] Figure 12 is a diagram of the base scissor structure in the embodiment of the present application;

[0036] Figure 13 is a diagram of the line ball of the base scissor structure in the embodiment of the present application;

[0037] Figure 14 is a diagram of the base scissor structure constituting the inner and outer polygons in the embodiment of the present application;

[0038] Figure 15 is a diagram of the base scissor structure constituting the inner and outer polygons when overlapping in the embodiment of the present application;

[0039] BRIEF DESCRIPTION OF DRAWINGS: 101 - inductance coil group, 102 - scissor folding arm, 103 - upper center component, 104 - lead screw, 105 - lower center component, 106 - motor, 107 - sliding guide rail; 201 - base scissor structure, peripheral base structure 202, operating connecting rod 203, upper layer operating mechanism 204, upper layer operating mechanism 205. DETAILED DESCRIPTION

[0040] In order to make the purpose, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the embodiments described below are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0041] An adjustable inductance coil, comprising a mechanical expansion and contraction mechanism, an inductance coil group 101, a plurality of connection points are present on the mechanical expansion and contraction mechanism, the inductance coil group 101 is fixed on the connection points, in the process of expansion and contraction of the mechanical expansion and contraction mechanism, the distance between adjacent connection points changes, so that the inductance coil group 101 does not produce excessive tension and does not occur overhang. In the present application, the inductance coil group 101 does not produce excessive tension and does not occur overhang specifically refers to the distance between the rigid fixed points of the inductance coil group 101 in the folding process does not change more than 5%.

[0042] As shown in Figures 1-3, in some embodiments, the mechanical expansion and contraction mechanism includes a lead screw 104, an upper center component 103, a lower center component 105, and six or more even number of scissor folding arms 102, wherein the upper center component 103 and the lower center component 105 are movably mounted on the lead screw 104 and can relatively approach or move away along the axis of the lead screw 104, the scissor folding arms 102 are arranged in a central symmetric form around the upper center component 103 and the lower center component 105, and the upper and lower end points on the inner side of each scissor folding arm 102 are movably connected with the upper center component 103 and the lower center component 105 respectively; the upper end points of the odd-numbered scissor folding arms 102 on the outer side and the lower end points of the even-numbered scissor folding arms 102 on the outer side are fixed with the inductance coil group 101 as connection points.

[0043] In this embodiment, a motor 106 is also connected to the lead screw 104, the lower center component 105 is mounted on the lead screw 104 through a bearing, and the upper center component 103 is mounted on the lead screw 104 through thread engagement, when the lead screw 104 rotates with the motor 106, the lower center component 105 does not move up and down along the lead screw 104, and the upper center component 103 moves up and down along the lead screw 104.

[0044] This embodiment also includes a plurality of sliding guide rails 107, which pass through the upper center component 103 and the lower center component 105, so that the planes of the upper center component 103 and the lower center component 105 always remain parallel.

[0045] Principle: Inductor coil group 101 is the minimum number of 6 in the vertical foldable, and must be even, to achieve the folding way of staggered up and down. Inductor coil group 101 is a plane regular polygon when fully open. When the inductor coil group 101 is folded, the upper end point of the odd number of scissor folding arm 102 outside moves relatively upward and inward (radial); the lower end point of the even number of scissor folding arm 102 outside moves relatively downward and inward (radial). Because of the restriction that the inductor coil group 101 does not generate excessive tension during folding, and does not occur hanging, that is, the total length of the connection point remains unchanged, the radial position and the vertical position of the connection point in the plane composed of the vertical axis and the radial direction need to meet the following elliptical formula:

[0046] Where x is the distance of the radial direction of the connection point to the center axis, taking positive value, z is the height of the connection point from the center plane, which can take positive and negative (i.e. upward or downward folding). R o is the radius of the circumscribed circle of the regular polygon after the inductor coil group 101 is fully unfolded, N s is the number of sides of the regular polygon after the inductor coil group 101 is fully unfolded.

[0047] As shown in Figure 4, the scissor linkage structure is fixed at one end, and the other end of the vertex trajectory naturally forms an ellipse (scaling principle). Therefore, it can be easily realized the trajectory required in formula (1).

[0048] In practical application, ignoring the thickness of the connecting rod, to achieve complete folding, the length of a single connecting rod on the scissor folding arm 102 should be equal to the length of the side of the regular polygon after the inductor coil group 101 is fully unfolded, that is:

[0049] Where L s represents the length of a single connecting rod on the scissor folding arm 102;

[0050] At this time, to achieve complete unfolding, the number of scissor folding arms 102 should satisfy that the length is equal to R o when fully unfolded, that is, the number of scissor folding arms 102 is equal to But It is not necessarily an integer, so it needs to be rounded down, so the number of scissor folding arms 102 is equal to:

[0051] Where N stage represents the number of scissor folding arms 102;

[0052] And the remaining part, can be compensated by the center component, so the upper center component 103 and the lower center component 105 are circles with a radius of R 补 , the formula is:

[0053] As shown in Figure 5, when N s =14, R0=30cm, L s When R = 13.35cm, 补 It is approximately 10% of R0. At this point, when scaling the structure, the distance variation (error) between two adjacent connection points is within 4mm, which will not cause coil sag or excessive tension in implementation. This error is independent of R0, but related to N. s Directly related, N s Numerically, this number equals the number of scissor folding arms 102. As shown in Figure 6, the inductor coil group 101, which can be implemented using connecting rods, has at least 6 sides. In this case, an equilateral triangle is formed between every two scissor folding arms 102, achieving a folding transformation with zero remainder and zero error. The drawback is that an intermediate component is required in the actual implementation, thus introducing errors. Furthermore, since there is only one stage of scissor folding arms 102, the compressed structure will be relatively long. A more suitable number of folding sides is 14, 20, 26, or 32, leaving sufficient space in the center to accommodate the central component that fixes the folding arms. Therefore, the preferred number of scissor folding arms 102 is 14, 20, 26, or 32.

[0054] The adjustable inductor coil of this invention exhibits a monotonically changing inductance during adjustment, as shown in Figure 7. The inductance value of the piecewise linear inductance during the change can be calculated using the line integral method. In the figure, R0 = 30cm, N s =14, the inductance value of a single-turn coil was calculated, and the inductance values ​​and equivalent circular radii of circular coils with the same top-view diameter were listed for comparison. Because the inductance of the invented adjustable inductor coil changes monotonically during adjustment, the inductance can be controlled using the following method:

[0055] An inductor control method, based on an adjustable inductor coil of the present invention, further includes a voltage and current sensor and a negative feedback controller. The method includes: using the voltage and current sensor to acquire the waveforms of voltage and current, thereby obtaining the current inductance value of the adjustable inductor coil; comparing the current inductance value with a target inductance value to obtain a difference; the negative feedback controller adjusting a motor 106 according to the difference, thereby making the inductance value of the adjustable inductor coil reach the target inductance value. The negative feedback controller adjusts the motor according to the amplitude of the measured current value or the phase with the voltage, so that the current reaches the target amplitude or phase.

[0056] As shown in FIG. 8-15, in some embodiments, the mechanical expansion and contraction mechanism comprises N basic scissors structures 201, a central operating mechanism, wherein the basic scissors structure 201 comprises two peripheral basic components 202, which are composed of two equal-length connecting rods, the two connecting rods are fixedly connected at the tail, the included angle between the two connecting rods is θ, and the length of the connecting rod is L0; the peripheral basic component 202 is shown in FIG. 11; the two peripheral basic components 202 of each basic scissors structure 201 overlap up and down at the central endpoint and are connected by a rotating shaft; the basic scissors structure 201 is shown in FIG. 12-13; N basic scissors structures 201 are connected by rotating shafts at the head and tail to form two inner and outer regular polygons, N is a natural number greater than 2; as shown in FIG. 14, the relationship between N and θ is:

[0057] Wherein each endpoint of the outer polygon is connected to the inductor coil group 101 as a connecting point; on the angle bisector of the upper and lower two layers of peripheral basic components 202 of more than one basic scissors structure 201, an operating connecting rod 203 with a length of L1 is fixed; wherein the calculation formula of L1 is:

[0058] The central operating mechanism comprises two layers, namely the upper operating mechanism 204 and the lower operating mechanism 205, wherein the upper operating mechanism 204 and the lower operating mechanism 205 are connected by a rotating shaft and the rotating shaft is arranged at the center point of the inner and outer regular polygons formed by the N basic scissors structures 201; the upper operating mechanism 204 and the upper operating connecting rod 203 are connected by a rotating shaft, and the lower operating mechanism 205 and the lower operating connecting rod 203 are connected by a rotating shaft.

[0059] Principle explanation: the basic scissors structure 201 is shown in FIG. 12-13, wherein FIG. 13 is a line ball diagram, the included angle between the two peripheral basic components 202 is α, and the angle difference is β; as shown in FIG. 14, there are N basic scissors structures 201, and the inner polygon has 2N sides, and the inner angle sum of the inner polygon should be equal to 180°×(2N-2); because all the connecting rods have equal lengths, the polygon ABCD in FIG. 14 is a rhombus, so the rhombus inner angle at point B (the outer angle of the inner polygon) is equal to 180°-β. The inner angle at point A of the inner polygon is: α=180°-β-θ

[0060] The inner angle at point B of the inner polygon is γ=360°-(180°-β)=180°+β

[0061] The inner angle sum of the inner polygon is (α+γ)N=(180°-β-θ+180°+β)N=180°×2N-Nθ=180°×(2N-2)=180°×2N-360°

[0062] So

[0063] As shown in Fig. 15, at this time, β = 0, the upper and lower peripheral base members 202 of each base scissor structure 201 coincide, at this time, the inner and outer polygons coincide, reaching the maximum position. At this time, the length of the operating link 203 should be equal to half the distance from the polygon end point to the center point, therefore, the L1 length is set as:

[0064] The above description is only the preferred embodiment of the present application, it should be pointed out that, for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. An adjustable inductance coil, characterized by The mechanical expansion and contraction mechanism has a plurality of connecting points, and the inductor coil group is fixed on the connecting points.

2. An adjustable inductor coil as claimed in claim 1, characterized in that The mechanical expansion and contraction mechanism includes a screw rod, an upper center component, a lower center component, and six or more pairs of scissors folding arms.

3. An adjustable inductor coil according to claim 2, wherein The motor is connected to the screw rod, the lower center component is mounted on the screw rod through a bearing, and the upper center component is mounted on the screw rod through thread engagement.

4. An adjustable inductor coil as claimed in claim 2, wherein The number of the scissors folding arms is 14, 20, 26, or 32.

5. An adjustable inductor coil as claimed in claim 2, wherein The length of the single link on the scissors folding arm is determined by the following equation: where L s represents the length of a single link on the scissor-folding arm 102; R o represents the radius of the circumscribed circle of the regular polygon after the complete unfolding of the set of inductive coils; N s represents the number of sides of the regular polygon when the set of inductive coils is fully deployed.

6. An adjustable inductor coil as claimed in claim 5, characterised in that The number of stages of the scissor folding arms is determined by the following formula: wherein N stage represents the number of scissor-folding arms; The upper and lower central assemblies are circular in shape, the radius of which is determined by the following formula: wherein R 补 denotes the radius of the upper and lower central components.

7. An adjustable inductor coil according to claim 6, wherein The voltage and current sensor is used to obtain the waveforms of the voltage and current, so as to obtain the current inductance value of the adjustable inductor coil.

8. A method of inductance control based on the adjustable inductance coil of claim 3, further comprising a voltage current sensor, a negative feedback controller, the method comprising: The negative feedback controller adjusts the motor according to the difference, so that the inductance value of the adjustable inductor coil reaches the target inductance value. The center operation mechanism includes two layers, namely an upper operation mechanism and a lower operation mechanism.

9. An adjustable inductor coil as claimed in claim 1, characterized in that The mechanical expansion and contraction mechanism comprises N basic scissors structures and a central operating mechanism, wherein the basic scissors structure comprises two peripheral basic components, the peripheral basic components are composed of two connecting rods with equal length, the two connecting rods are fixedly connected at the head and tail, the included angle between the two connecting rods is θ, and the length of the connecting rod is L0; the two peripheral basic components of each basic scissors structure are overlapped up and down at the central end point and are connected through a rotating shaft; the N basic scissors structures are connected through rotating shafts at the head and tail to form two regular polygons inside and outside, N is a natural number greater than 2; wherein the relationship between N and θ is: Each end point of the outer polygon is connected to the inductor coil group as a connecting point; the operating connecting rod with a length of L1 is fixed on the angle bisector of the upper and lower layers of the outer peripheral base member of the more than one base scissors structure; and the calculation formula of L1 is: The upper operation mechanism and the lower operation mechanism are connected through a rotating shaft, and the rotating shaft is arranged at the center point of the inner and outer regular polygons composed of N basic scissors structures. The upper operation mechanism and the upper operation link are connected in a rotating shaft mode, and the lower operation mechanism and the lower operation link are connected in a rotating shaft mode.

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