Small-size low-resonant-frequency receiving coil for wireless power transmission

Abstract

The invention provides a small-size low-resonant-frequency receiving coil for wireless power transmission. Comprising a spiral pipeline coil located in the middle, two planar spiral coils connected to the upper portion and the lower portion of the spiral pipeline coil in series, and two sets of circular dielectric plates and copper sheets which are stacked on the outer sides of the two planar spiral coils, wherein each copper sheet is formed by splicing a plurality of sectors. By adding the dielectric plate with high dielectric constant between the planar spiral coil and the copper sheet, the distributed capacitance is obviously increased, so that the receiving coil has lower resonant frequency when the size is smaller. The invention is suitable for some specific application scenarios, such as wireless energy supply of implantable medical equipment, use of electromagnetic radiation of a lower frequency band, and requirements of a smaller size and a lower resonant frequency of the receiving coil, so as to realize resonant transmission of electric energy from a transmitting end to a receiving end.

Description

Technical Field

[0001] The present invention relates to the fields of wireless power transmission technology, ferroelectric materials, and electromagnetic computing, and in particular to a small-sized low-resonance frequency receiving coil for wireless power transmission. Background Art

[0002] Implantable medical devices, mobile robots, portable electronic devices, etc. are increasingly being used and are gradually developing in the direction of intelligence, miniaturization, and convenience. Typically, capsule robots, as an implantable medical device, are usually powered by tow cables or batteries in the early days. The tow cables will affect the movement of the capsule robot and may cause damage to the intestines; the battery capacity is limited and cannot work for a long time, and there are also problems such as life and cost. After years of development, WPT (Wireless Power Transmission) technology has made significant progress and has been widely used. The application of WPT technology in implantable medical devices has obvious advantages: it can solve problems such as poor battery power supply durability and high cost, reduce the pain of patients caused by repeated surgery, and improve the quality of life of patients.

[0003] WPT technology is used to provide electrical energy to implantable medical devices. Since implantable devices need to enter the body and may move within a certain range (such as gastrointestinal capsule robots), there is a certain distance between the internal receiving coil and the external transmitting coil. For this reason, electromagnetic radiation with a lower frequency band is usually used to generate a stronger magnetic field within a certain spatial range. On the other hand, the size of the internal receiving coil is required to be small, but the resonant frequency is low, so as to achieve resonant transmission of electrical energy from the transmitting end to the receiving end. A receiving coil with a small and compact size and a low resonant frequency has become an important research topic. Summary of the invention

[0004] The present invention provides a small-size, low-resonance frequency receiving coil to meet the application requirements of specific occasions and use WPT technology to provide electric energy.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The receiving coil has a compact design structure: it includes a spiral tube coil in the middle, two planar spiral coils connected in series above and below the spiral tube coil, and two groups of circular dielectric plates and copper sheets stacked outside the two planar spiral coils.

[0007] For the magnetic resonance wireless power transmission system, the transmitter and the receiver are in a resonant state, that is, The transmission efficiency is highest when

[0008] In some applications, such as WPT systems in implantable medical devices, electromagnetic radiation in a lower frequency band is usually used to generate a strong magnetic field in a certain spatial range, and the size of the receiving coil placed in the body is required to be small. Small-sized receiving coils often have a higher resonant frequency, and it is not easy to achieve resonant transmission of electric energy from the transmitter to the receiver. Therefore, two groups of circular dielectric plates and copper sheets stacked on the outside of two planar spiral coils are used to significantly increase the distributed capacitance, so that the receiving coil has a lower resonant frequency when the size is small.

[0009] Preferably, the whole is a cylindrical structure with a relatively small spatial dimension, such as a diameter of 25.55 mm and a height of 4.55 mm.

[0010] Preferably, the structures of the spiral tube coil and the two-plane spiral coil are optimized so that the receiving coil has a larger inductance.

[0011] Preferably, the distributed capacitance is significantly increased by adding a dielectric plate with a high dielectric constant between the planar spiral coil and the copper sheet.

[0012] Preferably, the dielectric plate with a high dielectric constant can be made of materials such as barium titanate-based ceramics.

[0013] Preferably, the copper sheet outside the circular dielectric plate is composed of a plurality of sector-shaped copper sheets, and there is a gap along the radial direction between the sector-shaped copper sheets to reduce the eddy current loss when the receiving coil is working. 3 For ferroelectric materials with a capacitance of 0.5 mm and a thickness of 0.5 mm, simulation results show that the parasitic capacitance of the receiving coil can be increased from 1 pF to 1 nF or 10 nF.

[0014] Preferably, by taking the above measures and increasing the inductance and capacitance, the receiving coil has a lower resonance frequency (lower than 1 MHz) when the size is small.

[0015] The technical solution provided by the present invention has at least the following technical effects:

[0016] 1. The receiving coil proposed in the present invention has a small and compact structure, such as a cylindrical shape with a diameter of 25.55 mm and a height of 4.55 mm.

[0017] 2. The receiving coil proposed in the present invention has a relatively large inductance value.

[0018] 3. The receiving coil proposed in the present invention has significantly increased distributed capacitance.

[0019] 4. The receiving coil proposed in the present invention has a lower resonance frequency.

[0020] 5. The receiving coil proposed in the present invention can be used in a WPT system that provides power to implantable medical devices, mobile robots, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0022] Figure 1 A schematic diagram of the structure of various components in a small-size, low-resonance frequency receiving coil for WPT provided by the present invention;

[0023] Figure 2 A schematic diagram of the overall structure of a small-size, low-resonance frequency receiving coil for WPT provided by the present invention;

[0024] Figure 3 is the distributed capacitance value of the receiving coil of Example 1 when the dielectric plates have different dielectric constants. Wherein, C0=1.03pF is the distributed capacitance value of the comparative example 1 when the two sets of dielectric plates and copper sheets stacked above and below the planar spiral coil are removed;

[0025] Figure 4 is the resonant frequency of the receiving coil of Example 1 when the dielectric plates have different dielectric constants. Wherein, F0=48.27MHz is the resonant frequency when the two sets of dielectric plates and copper sheets stacked above and below the planar spiral coil are removed in Comparative Example 1;

[0026] Figure 5 This is a schematic diagram of the overall structure of the receiving coil of Comparative Example 2;

[0027] Figure 6 This is a schematic diagram of the structure of the components of the receiving coil of comparative example 2. DETAILED DESCRIPTION

[0028] Embodiment 1:

[0029] As attached Figure 1 and 2 As shown, an embodiment of the present invention provides a small-size low-resonance frequency receiving coil for WPT, including a spiral tube coil in the middle position, two planar spiral coils connected in series above and below the spiral tube coil, and two groups of circular dielectric plates and copper sheets stacked on the outside of the two planar spiral coils.

[0030] The structure and size of each component in the receiving coil are as follows: the number of turns of the solenoid coil is N2 = 20 turns, the line width W2 = 0.4mm, the line height h2 = 0.035mm, the turn spacing P2 = 0.16mm, the outer diameter D = 25.55mm, and the height H2 = 3.28mm; the number of turns of the planar spiral coil is N1 = 20 turns, the line width W1 = 0.40mm, the line height h1 = 0.035mm, the turn spacing P1 = 0.50mm, the inner diameter R1 = 5mm, and the outer diameter R2 = 25.55mm; the thickness of the dielectric plate is h3 = 0.5mm, the diameter D = 25.55mm, and the dielectric constant is 2000F / m; the thickness of the copper sheet is h4 = 0.1mm, and the diameter D = 25.55mm. The relationship between the coil diameter and the size of each component is: the receiving coil diameter D = D1 + 0.5P + (2N1 + 1) W + (2N1-1) S. Where S = PW.

[0031] The capacitance, inductance and resonant frequency of the receiving coil are investigated through simulation. During the simulation, current source excitation is used, and the external space medium is set to air. The relationship between the simulated distributed capacitance and the dielectric constant of the dielectric plate is shown in the attached figure. Figure 3 The relationship between the resonant frequency and the dielectric constant of the dielectric plate is shown in the attached figure. Figure 4 As shown. It can be seen that the dielectric constant of the dielectric plate can significantly increase the distributed capacitance and reduce the resonant frequency. When the dielectric constant is 2000F / m, the capacitance C of the coil is 32.60nF and the resonant frequency of the coil is 0.32MHz.

[0032] The receiving coil with a diameter of 25.55mm, a height of 4.55mm and a resonant frequency of 0.32MHz can be used as a receiving coil in a WPT system that provides power to implantable medical devices, mobile robots, etc.

[0033] Comparative Example 1:

[0034] In this comparative example 1, on the basis of Example 1, the two sets of dielectric plates and copper sheets stacked above and below the planar spiral coil are removed, and other conditions are the same as those of Example 1. During the simulation, current source excitation is adopted, and the external space medium is set to air. The simulation results show that the coil capacitance C is 1.03pF, the inductance L is 10.58μH, and the resonant frequency of the coil is 48.27MHz. It can be seen that when the dielectric plate and copper sheet are removed from the transmitting coil, compared with Example 1, the resonant frequency of this comparative example is 150 times that of Example 1. It shows that the receiving coil designed in Example 1 can effectively reduce the self-resonant frequency under the condition that the outer dimensions of the receiving coil are constant.

[0035] Comparative Example 2:

[0036] This comparative example is a common structure of a receiving coil of an implantable medical wireless energy transmission system: a spiral tube coil in the middle, two printed planar spiral coils (P-PSC) attached to the F4BM substrate connected in series above and below the spiral tube coil, as shown in the attached figure. Figure 5 , 6 shown.

[0037] The structure and dimensions of the components in the receiving coil are as follows: the outer diameter of the solenoid coil is 26.00mm, the height is 4.55mm, the number of turns is 20, and the coil wire diameter is 0.16mm. The number of turns of the P-PSC is 20, the inner diameter is 14.00mm, the outer diameter of the coil is 26.00mm, the wire height is 0.035mm, and the wire width is 0.4mm. The thickness of the P-PSC is 0.5mm.

[0038] The capacitance, inductance and resonant frequency of the receiving coil are investigated by simulation. In the simulation, current source excitation is adopted and the external space medium is set as air. The simulation result shows that the resonant frequency of the coil is 10.37MHz

[0039] It can be seen that the receiving coil of the general wireless energy transmission system in comparative example 2 has a diameter of 26.00 mm and a height of 4.55 mm, and its resonant frequency is 10.37 MHz, which is significantly higher than the receiving coil of embodiment 1, indicating that the receiving coil designed by the present invention can effectively reduce the self-resonant frequency when the outer dimensions are similar.

Claims

1. A small-size, low-resonance-frequency receiving coil for wireless power transmission, characterized in that: The invention comprises a spiral tube coil in the middle, two planar spiral coils connected in series above and below the spiral tube coil, and two groups of circular dielectric plates and copper sheets stacked outside the two planar spiral coils.

2. A small-size, low-resonance frequency receiving coil for wireless power transmission according to claim 1, characterized in that: The overall spatial structure of the receiving coil is a cylinder with a diameter of 25.55mm and a height of 4.55mm.

3. A small-size low-resonance frequency receiving coil for wireless power transmission according to claim 1, characterized in that: The copper sheet on the outer side of the circular dielectric plate is formed by splicing a plurality of sector-shaped copper sheets, and there is a gap along the radial direction between the sector-shaped copper sheets to reduce the eddy current loss when the receiving coil is working.

4. The small-size low-resonance frequency receiving coil for wireless power transmission according to claim 1, characterized in that: The dielectric plate between the planar spiral coil and the copper sheet has a dielectric constant of 10 3 Ferroelectric material with a capacitance of the order of 1pF and a thickness of 0.5mm; the parasitic capacitance of the receiving coil increases from the order of 1pF to the order of 1nF or 10nF.

5. The small-size low-resonance frequency receiving coil for wireless power transmission according to claim 1, characterized in that: The resonant frequency of the receiving coil is below 1MHz.

6. A small-size, low-resonance-frequency receiving coil for wireless power transmission according to claim 1, characterized in that: The receiving coil is suitable for wireless power transmission systems that provide power to implantable medical devices, mobile robots, and portable electronic devices.

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