Fiber type super capacitor coil for wireless charging and real-time wireless voltage detection

Abstract

The invention provides a fiber type super capacitor coil for wireless charging and real-time wireless voltage detection. The fiber type super capacitor coil comprises a spiral fiber type energy storage coil, a reading coil and a variable capacitance diode, the anode of the fiber type energy storage coil is connected with the cathode of the variable capacitance diode, and the cathode of the fiber type energy storage coil is connected with the anode of the variable capacitance diode, so that the fiber type energy storage coil and the variable capacitance diode form an LC resonance unit; the reading coil and the inductance type fiber energy storage coil are coaxially arranged at an interval; and the reading coil is connected with a test port of the vector network analyzer through a microwave high-frequency connector.

Description

Technical Field

[0001] The invention relates to a fiber-type supercapacitor coil for wireless charging and real-time wireless voltage detection. Background Art

[0002] The multifunctional integration and miniaturization trend of wearable electronic devices is driving the evolution of various user interaction and monitoring units towards high-density integration. In this process, the wireless charging capability of energy storage modules has become a key technical node for improving the portability and intelligence of devices, directly affecting the freedom of form and user experience of system design.

[0003] As one of the core directions of innovation in wearable devices, wireless charging technology realizes contactless energy transmission through electromagnetic induction, which significantly reduces the complexity of user operations while optimizing the charging process. However, the current technical system faces adaptability challenges in the application of flexible scenarios: traditional rigid electromagnetic coils and signal processing units not only mismatch the mechanical properties of flexible substrates, but also restrict wearing comfort. On the other hand, the real-time determination of the operating status of the device is highly dependent on transient voltage monitoring. Existing solutions based on wired transmission or Bluetooth protocols are susceptible to additional energy consumption, resulting in a shortened operating cycle of the entire machine. Therefore, the development of passive wireless voltage sensing technology without additional energy consumption has become the key to breaking the deadlock.

[0004] For supercapacitors, due to their low energy density and fast charging and discharging speeds, their voltage often fluctuates. In most application scenarios, capacitors must be connected in series to provide the voltage required by electrical appliances. Manufacturing and environmental differences may lead to differences in internal impedance and aging rates, thereby affecting the operation, performance and safety of the battery pack. Therefore, it is necessary to perform accurate real-time voltage monitoring of supercapacitor multi-modules.

[0005] Although fiber supercapacitors (FSCs) have successfully achieved flexible integration with wireless charging functions and functional verification of practical applications, their voltage monitoring still relies on wired circuits and cannot build a complete wireless system. Summary of the invention

[0006] The main technical problem to be solved by the present invention is to realize remote real-time monitoring of the voltage state of the fiber-type supercapacitor.

[0007] In order to solve the above technical problems, the present invention provides a fiber-type supercapacitor coil for wireless charging and real-time wireless voltage detection, comprising: a spiral fiber-type energy storage coil, a reading coil and a varactor diode;

[0008] The positive electrode of the fiber-type energy storage coil is connected to the cathode of the varactor diode, and the negative electrode is connected to the anode of the varactor diode to form an LC resonance unit with the fiber-type energy storage coil and the varactor diode;

[0009] The reading coil is coaxial with the inductive fiber type energy storage coil and is placed at intervals; the reading coil is connected to the test port of the vector network analyzer through a microwave high-frequency connector.

[0010] In a preferred embodiment: the reading coil is made of enameled copper wire with a diameter of 0.5 mm and is wound into a ring structure with a diameter of 2 cm.

[0011] In a preferred embodiment: the production of the LC resonance unit includes the following steps:

[0012] 1) Prepare the coating slurry: add polyvinylidene fluoride to a beaker containing N-methylpyrrolidone, stir at room temperature until the polyvinylidene fluoride is completely dissolved, then add conductive carbon black to the beaker and stir, then add supercapacitor activated carbon and stir until all solids are evenly mixed;

[0013] 2) Add Na2SO4 to a beaker filled with deionized water and stir until the Na2SO4 is completely dissolved. Then add sodium carboxymethyl cellulose to the beaker in several batches. Seal the beaker with aluminum plastic film to prevent water evaporation during heating. Continue stirring in a 60°C water bath until the solid is completely dissolved and no lumps exist in the liquid.

[0014] 3) The slurry is coated on the metal current collector to make the electrode, and then placed in a vacuum drying oven for 24 hours to remove the solvent to obtain the positive and negative electrodes of the fiber-type energy storage coil;

[0015] 4) Take the positive and negative electrodes, and smoothly wrap the separator cut into long strips on one of the electrodes so that it completely covers the slurry on the surface of the current collector; then twist the two electrodes together into a spiral structure to obtain a fiber-type electrode;

[0016] 5) Place the fiber-type electrode into a heat shrink tube, inject gel electrolyte, and seal the tube opening with epoxy resin;

[0017] 6) Winding the prepared fiber-type energy storage coil into a spiral coil;

[0018] 7) The positive electrode of the prepared fiber-type energy storage coil is connected to the cathode of the varactor diode, and the negative electrode is connected to the anode of the varactor diode, thereby forming a fiber-type supercapacitor coil with inductance function, namely, an LC resonance unit.

[0019] In a preferred embodiment: the equivalent input impedance of the LC resonance unit is expressed as:

[0020]

[0021] in, and represents the angular frequency and mutual inductance between the reading coil and the inductive fiber type energy storage coil, and Represents the equivalent inductance and capacitance of the LC resonant unit, represents the equivalent resistance of the LC resonant unit, Is an imaginary unit.

[0022] In a preferred embodiment: the equivalent input impedance of the reading coil ( ) is expressed as:

[0023]

[0024] in, and Represent the resistance and inductance of the reading coil respectively.

[0025] In a preferred embodiment: In a single-port measurement system, the input return loss The parameters can be expressed as:

[0026]

[0027] in, When the value is 0, it means that the circuit is in an ideal matching state, that is, the characteristic impedance is Input return loss The minimum value of corresponds to the natural resonant frequency of the LC resonant unit.

[0028] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0029] The present invention provides a fiber-type supercapacitor coil for wireless charging and real-time wireless voltage detection, which uses a fiber-type supercapacitor coil with an inductance function to act as an inductance coil for wireless charging and an LC resonance unit for wireless voltage monitoring, thereby realizing the integration of energy storage, wireless charging and wireless voltage sensing. The device structure is simplified, and ideas are provided for multi-module power management. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the manufacturing process of a fiber-type energy storage coil in a preferred embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the connection between the fiber-type energy storage coil and the diode in a preferred embodiment of the present invention;

[0032] Figure 3 This is a charging principle diagram of a fiber-type energy storage coil supercapacitor coil in a preferred embodiment of the present invention;

[0033] Figure 4An equivalent circuit diagram of a fiber-type supercapacitor coil in a preferred embodiment of the present invention;

[0034] Figure 5 A voltage variation curve diagram of a wireless charging station charging different numbers of fiber-type supercapacitors in a preferred embodiment of the present invention;

[0035] Figure 6 The frequency-voltage variation trend diagram of the fiber-type supercapacitors with 4-10 turns in the preferred embodiment of the present invention;

[0036] Figure 7 The sensitivity factor variation trend diagram of the fiber-type supercapacitors of 4-10 circles in the preferred embodiment of the present invention;

[0037] Figure 8 This is a curve diagram of the S11 parameter change before and after charging when four groups of fiber-type supercapacitors are wirelessly charged simultaneously in a preferred embodiment of the present invention;

[0038] Fig. 9 This is a frequency variation trend diagram before and after charging when four groups of fiber-type supercapacitors are wirelessly charged simultaneously in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the technical solutions and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0040] refer to Figure 1 This embodiment provides a fiber-type energy storage coil, the production of which includes the following steps:

[0041] 1) Prepare the required coating slurry, take 0.3 g of polyvinylidene fluoride (PVDF) and add it to a small beaker containing 13 ml of N-methylpyrrolidone (NMP), stir at room temperature for 1 hour until PVDF is completely dissolved, then add 0.3 g of conductive carbon black (Super P) to the beaker and stir for 1 hour until it is uniform. After it is fully dissolved, add 2.4 g of supercapacitor activated carbon and stir for 2 hours until all solids are fully and evenly mixed.

[0042] 2) Take 14.2 g of Na2SO4 and add it to a beaker containing 100 ml of deionized water. Stir until the soil is completely dissolved. Then take 1.1 g of sodium carboxymethyl cellulose (CMC) and add it to the solution several times. Seal the mouth of the beaker with aluminum plastic film to prevent water evaporation during heating. Continue stirring in a 60°C water bath for 2 h until the solid is completely dissolved and there are no lumps in the liquid.

[0043] 3) The slurry is coated on the metal current collector to make the electrode, and then placed in a vacuum drying oven for 24 hours to remove the solvent to obtain the positive and negative electrodes of the energy storage unit.

[0044] 4) Take the positive and negative electrodes, and smoothly wrap the separator cut into long strips on one of the electrodes to completely cover the active material on the surface of the current collector to prevent short circuit caused by direct contact between the two electrodes. Then twist the two electrodes together into a spiral structure to reduce the distance between the electrodes and reduce the internal resistance.

[0045] 5) Place the fiber-type electrode into a heat shrink tube, inject gel electrolyte, and seal the tube opening with epoxy resin.

[0046] 6) Wind the prepared fiber-type energy storage coil into a spiral coil shape.

[0047] One end of the positive electrode of the prepared fiber-type energy storage coil and the other end of the negative electrode are connected through a diode, wherein the anode of the diode is connected to the negative electrode of the fiber-type energy storage coil, and the cathode of the diode is connected to the positive electrode of the fiber-type energy storage coil to form an LC resonance unit, thereby obtaining a fiber-type supercapacitor coil that can be wirelessly charged, such as Figure 2 shown.

[0048] Then, the fiber-type energy storage coil supercapacitor coil and the diode are placed on the same axis as the reading coil and wirelessly charged. The equivalent circuit diagram is as follows: Figure 4 As shown in FIG, a real-time voltage monitoring system during wireless charging is obtained. Within a certain distance, the fiber-type energy storage coil supercapacitor coil and the coil of the charging base form a near-field coupling, thereby realizing wireless charging, as shown in FIG. Figure 3 As shown. The spiral fiber-type electrode acts as a near-field coupled antenna, realizing the integration of energy harvesting and storage. In order to explore the feasibility of this system in real life, 1 to 10 groups of fiber-type energy storage coil supercapacitor coils are connected in series into a disc shape and charged with 1Hz pulses in a commercial wireless charging station. This system can still perform high-efficiency wireless charging, and its charging voltage change is shown in Figure 5. As the number of groups increases, the voltage can be directly superimposed, and since the devices are all within the near-field charging range, the charging speed of single and multiple groups increases proportionally.

[0049] The reading coil is made of 0.5 mm diameter enameled copper wire wound into a 2 cm diameter ring structure, and connected to the test port of the vector network analyzer (VNA) through a microwave high-frequency connector (Subminiature Version A, SMA). The near-field electromagnetic coupling between the reading coil and the inductive fiber energy storage coil is used to wirelessly obtain the sensor resonant frequency.

[0050] The equivalent input impedance of the LC resonant unit can be expressed by equation (1):

[0051] (1)

[0052] in, and represents the angular frequency and mutual inductance between the reading coil and the sensor coil inductive fiber type energy storage coil, and Represents the equivalent inductance and capacitance of the LC resonant unit, represents the equivalent resistance of the LC resonant unit, Is an imaginary unit.

[0053] The equivalent input impedance of the external coupled reading coil ( )is expressed as formula (2):

[0054] (2)

[0055] in, and Represent the resistance and inductance of the reading coil respectively.

[0056] In a one-port measurement system, the input return loss The parameters can be expressed as formula (3):

[0057] (3)

[0058] in, When the value is 0, it means that the circuit is in an ideal matching state, that is, the characteristic impedance is . Input return loss The minimum value of corresponds to the natural resonant frequency of the LC resonator. Therefore, by measuring the minimum By adjusting the value, the remote contactless detection of the resonant frequency of the LC resonator can be achieved.

[0059] Therefore, real-time acquisition of voltage information of the inductive fiber energy storage coil is a key prerequisite for the efficient operation of its power management system. To achieve non-invasive voltage monitoring, this embodiment proposes a sensing strategy based on spectrum analysis: the spiral electrodes of the inductive fiber energy storage coil are reconstructed into RF signal transceiver antennas, and their own topological characteristics are used for electromagnetic response modulation. By forming an LC resonant unit with the inductive fiber energy storage coil and the encapsulated diode, the series resonator ( ) and capacitance ( ) parameters will determine its resonant frequency characteristics. This frequency can be expressed as formula (4):

[0060] (4)

[0061] Based on the above real-time monitoring requirements, this embodiment replaces the traditional rectifier diode with the FV1043 varactor diode and integrates it into the fiber-type energy storage coil supercapacitor coil, forming a fiber-type supercapacitor coil with inductance function, and further forming a tunable LC resonant circuit.

[0062] The reading coil, fiber-type energy storage coil and supercapacitor coil are placed on the same axis, and the wireless charging monitoring system is constructed by combining the LC resonance principle, and a dual-resonance coupling topology is constructed. The vector network analyzer is used to scan the frequency in real time to monitor The resonant frequency offset corresponding to the minimum value of the parameter , realizing non-contact measurement of FSC voltage during charging process, its core feature is to realize signal modulation by utilizing the capacitance-voltage nonlinear response characteristics of the variable capacitance element.

[0063] At the same time, when the variable capacitance diode is in the reverse cutoff operating range, its junction capacitance characteristics show significant voltage dependence: as the reverse bias voltage increases, the equivalent capacitance of the diode decreases nonlinearly. In the system operation state, this coupling effect causes the resonant frequency of the fiber supercapacitor to drift positively with the increase of voltage.

[0064] from Figure 6 and 7 It can be found that each group of fiber supercapacitor coil windings corresponds to different voltages. Parameter curve and frequency. Therefore, fiber-type energy storage coil supercapacitor coils of different lengths can produce a frequency gradient within a fixed range in the resonant frequency band, realizing voltage encoding within a dynamic range such as Figure 6 , that is, fiber-type energy storage coils of different lengths have their own frequency variation range. And through research, it is found that the sensitivity factors of fiber-type energy storage coils of different lengths and supercapacitor coils are highly consistent, such as Figure 7As shown. This feature provides a theoretical basis for achieving precise control of the resonant frequency through structural design. By optimizing the geometric parameters of the fiber-type energy storage coil supercapacitor coil, its resonant frequency can be adjusted to a specific frequency band, thereby achieving real-time wireless monitoring of the voltage state of a single fiber-type energy storage coil supercapacitor coil during charging. This mechanism breaks through the physical limitations of traditional wired monitoring and lays a key technical foundation for building a passive wireless voltage monitoring system.

[0065] In order to verify the applicability of this integrated system, in this embodiment, the voltage of a self-made capacitor disk with four fiber-type energy storage coils and supercapacitor coils of different lengths connected in series was dynamically monitored. The actual system consists of a fiber-type energy storage coil supercapacitor coil, a charging module and a voltage monitoring module. Real-time voltage monitoring can be performed during wireless charging. The wireless charging distance can reach 4 cm, and the voltage can be wirelessly monitored at a distance of 3 cm. Since the size is much smaller than the charging coil, the basic frequency of each fiber-type energy storage coil supercapacitor coil is increased, and its S11 frequency changes as shown in the figure. Figure 8 After the fiber-type energy storage coil supercapacitors in the capacitor disk are connected in series, the changes in the resonant frequency of the four fiber-type supercapacitors before and after charging can be clearly observed in the S11 curve, as shown in Figure 1. Fig. 9 As shown, the voltage of the fiber supercapacitor can be dynamically monitored during the charging process. Based on this system, this embodiment realizes the simultaneous monitoring of the voltage changes of multiple charging modules, which can easily detect which module has a fault and quickly identify it. At the same time, this passive voltage detection does not require additional power support, so even if the entire capacitor energy storage device is out of power, the voltage state of the entire device can be detected, realizing the intelligence of the power supply system.

[0066] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A fiber-type supercapacitor coil for wireless charging and real-time wireless voltage detection, characterized in that include: Spiral fiber-type energy storage coil, reading coil and varactor diode; The positive electrode of the fiber-type energy storage coil is connected to the cathode of the varactor diode, and the negative electrode is connected to the anode of the varactor diode to form an LC resonance unit with the fiber-type energy storage coil and the varactor diode; The reading coil is coaxial with the inductive fiber type energy storage coil and is placed at intervals; the reading coil is connected to the test port of the vector network analyzer through a microwave high-frequency connector.

2. The fiber-type supercapacitor coil for wireless charging and real-time wireless voltage detection according to claim 1, characterized in that: The reading coil is made of enameled copper wire with a diameter of 0.5 mm and is wound into a ring structure with a diameter of 2 cm.

3. The fiber-type supercapacitor coil for wireless charging and real-time wireless voltage detection according to claim 1, characterized in that: The production of the fiber type energy storage coil LC resonance unit comprises the following steps: 1) Prepare the coating slurry: add polyvinylidene fluoride to a beaker containing N-methylpyrrolidone, stir at room temperature until the polyvinylidene fluoride is completely dissolved, then add conductive carbon black to the beaker and stir, then add supercapacitor activated carbon and stir until all solids are evenly mixed; 2) Add Na2SO4 to a beaker filled with deionized water and stir until the Na2SO4 is completely dissolved. Then add sodium carboxymethyl cellulose to the beaker in several batches. Seal the beaker with aluminum plastic film to prevent water evaporation during heating. Continue stirring in a 60°C water bath until the solid is completely dissolved and no lumps exist in the liquid. 3) The slurry is coated on the metal current collector to make the electrode, and then placed in a vacuum drying oven for 24 hours to remove the solvent to obtain the positive and negative electrodes of the fiber-type energy storage coil; 4) Take the positive and negative electrodes, and smoothly wrap the separator cut into long strips on one of the electrodes so that it completely covers the slurry on the surface of the current collector; then twist the two electrodes together into a spiral structure to obtain a fiber-type electrode; 5) Place the fiber-type electrode into a heat shrink tube, inject gel electrolyte, and seal the tube opening with epoxy resin; 6) Winding the prepared fiber-type energy storage coil into a spiral coil; 7) The positive electrode of the prepared fiber-type energy storage coil is connected to the cathode of the varactor diode, and the negative electrode is connected to the anode of the varactor diode, thereby forming a fiber-type supercapacitor coil with inductance function, namely, an LC resonance unit.

4. The fiber-type supercapacitor coil for wireless charging and real-time wireless voltage detection according to claim 1, characterized in that: The equivalent input impedance of the LC resonance unit is expressed as: ； in, and represents the angular frequency and mutual inductance between the reading coil and the inductive fiber type energy storage coil, and Represents the equivalent inductance and capacitance of the LC resonant unit, represents the equivalent resistance of the LC resonant unit, Is an imaginary unit.

5. The fiber-type supercapacitor coil for wireless charging and real-time wireless voltage detection according to claim 4, characterized in that: The equivalent input impedance of the reading coil ( ) is expressed as: ； in, and Represent the resistance and inductance of the reading coil respectively.

6. The fiber-type supercapacitor coil for wireless charging and real-time wireless voltage detection according to claim 5, characterized in that: In a one-port measurement system, the input return loss The parameters can be expressed as: ； in, When the value is 0, it means that the circuit is in an ideal matching state, that is, the characteristic impedance is Input return loss The minimum value of corresponds to the natural resonant frequency of the LC resonant unit.

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