Electric field coupling wireless electric energy transmission system and control method thereof

Abstract

The invention discloses an electric field coupling wireless power transmission system and a control method thereof. The control method comprises the steps that autonomous multiphase current feed push-pull inverters with full-resonance and zero-voltage switching operation are symmetrically adopted at a transmitting end and a receiving end, and full-ZVS operation autonomy of the electric field coupling wireless power transmission system is achieved; the autonomous characteristic of the system is embodied in that the system can automatically track the frequency for realizing the same phase of voltage and current, the frequency is a constant-voltage and constant-current switching point, and the constant-current charging or constant-voltage charging of the system and the switching between the constant-current charging and the constant-voltage charging of the system can be realized by adjusting the frequency of the inverter, namely the working frequency of the system, based on the constant-voltage and constant-current switching point; according to the invention, the system is simple in structure, does not need to add an extra switching device or needs a complex control circuit, is higher in transmission efficiency and reliability, improves the flexibility and adaptability of the system, and also guarantees the high-efficiency energy transmission and low electromagnetic interference characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transfer, and particularly to an electric-field coupled wireless power transfer system and a control method thereof. Background Art

[0002] Wireless Power Transfer (WPT) technology is a new technology that realizes the transfer of electrical energy from a power source to a load without electrical contact through electromagnetic waves or mechanical waves. Since there is no physical connection between the power source and the load during the transfer process of WPT technology, various potential hazards caused by hardware connections are avoided, greatly improving the flexibility of electrical equipment. Among them, the Electric-field Coupled Power Transfer (ECPT) technology has the following advantages: 1) The coupling mechanism has low cost, light weight, and is easy to change in shape; 2) The magnetic field interference around the coupling mechanism is relatively low; 3) It can transfer energy across metal obstacles; 4) The eddy current loss caused on the metal conductor between or around the coupling mechanisms is very small. Therefore, the ECPT technology is more suitable for applications that require high flexibility and low interference.

[0003] Currently, there is little research on electric-field coupled wireless power transfer systems suitable for constant current / constant voltage output. In the practical application of ECPT technology, some electrical devices require the system to have constant current or constant voltage output characteristics, that is, the output voltage or current of the system is decoupled from the load. In addition, the system also needs to have the function of switching between constant current and constant voltage modes as required. The solutions in the existing literature mainly set up detection circuits and control circuits at the output end and input end of the system, and control the input voltage according to the detected load voltage to achieve a constant output of the system, or achieve a constant output of the system through the characteristics of the resonant network and the corresponding parameter design methods. However, although these methods can achieve constant current or constant voltage output, they usually require complex control circuits or additional switching devices. Some scholars have proposed a constant voltage type electric-field coupled wireless power transfer system based on a bilateral F-LCLC network, which realizes the switching of the system between constant current and constant voltage working modes by adding a control switch in the resonant network and controlling the on-off of the control switch. Such a design increases the cost and volume of the system and affects the reliability of the system. Summary of the Invention

[0004] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title. However, such simplifications or omissions shall not be used to limit the scope of the present invention.

[0005] In view of the above existing problems, the present invention is proposed.

[0006] Therefore, the present invention provides an electric field coupling wireless power transmission system and its control method, which can solve the problems mentioned in the background art.

[0007] To solve the above technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides an electric field coupling wireless power transmission system, including: a transmitting end and a receiving end;

[0009] The transmitting end at least includes a DC power supply, an inverter circuit, and a primary resonant compensation circuit;

[0010] The receiving end at least includes a secondary resonant compensation circuit designed for the primary resonant compensation circuit, a rectifier circuit, and a target load.

[0011] As a preferred embodiment of the electric field coupling wireless power transmission system of the present invention, further including:

[0012] The primary resonant compensation circuit includes a plurality of inductors and a plurality of capacitors;

[0013] The secondary resonant compensation circuit includes a plurality of inductors and a plurality of capacitors;

[0014] The secondary resonant compensation circuit is symmetrically arranged with the primary resonant compensation circuit.

[0015] As a preferred embodiment of the electric field coupling wireless power transmission system of the present invention, further including:

[0016] The inverter circuit includes a plurality of inductors, a plurality of capacitors, and a plurality of MOS transistors;

[0017] The rectifier circuit includes a plurality of inductors, a plurality of capacitors, and a plurality of MOS transistors;

[0018] The structures and parameters of the inverter circuit and the rectifier circuit are symmetrically arranged.

[0019] As a preferred embodiment of the electric field coupling wireless power transmission system of the present invention, the transmitting end and the receiving end include:

[0020] The transmitting end further includes a first transmitting plate and a second transmitting plate;

[0021] The receiving end further includes a first receiving plate and a second receiving plate;

[0022] The first transmitting plate, the second transmitting plate, the first receiving plate, and the second receiving plate form an electric field coupling mechanism.

[0023] As a preferred embodiment of the electric field coupling wireless power transmission system of the present invention, it further includes:

[0024] The first transmitting electrode plate and the second transmitting electrode plate are connected to the primary resonant compensation circuit;

[0025] The first receiving electrode plate and the second receiving electrode plate are connected to the secondary resonant compensation circuit;

[0026] The positive pole of the DC power supply is connected to the first DC input terminal, and the negative pole of the DC power supply is connected to the second DC input terminal;

[0027] Any one end of the target load is connected to the first DC output terminal, and the other end is connected to the second DC output terminal.

[0028] As a preferred embodiment of the electric field coupling wireless power transmission system of the present invention, it further includes:

[0029] The output of the inverter circuit is the first AC output terminal and the second AC output terminal, and the first AC output terminal and the second AC output terminal are connected to the primary resonant compensation circuit;

[0030] The input of the rectifier circuit is the first AC input terminal and the second AC input terminal, and the first AC input terminal and the second AC input terminal are connected to the secondary resonant compensation circuit.

[0031] As a preferred embodiment of the electric field coupling wireless power transmission system of the present invention, it further includes: Filter capacitors are connected in parallel at both ends of the target load.

[0032] In a second aspect, the present invention provides a control method for an electric field coupling wireless power transmission system, including:

[0033] Determine the load resistance value at the time of constant voltage and constant current switching;

[0034] Calculate the corresponding first equivalent load according to the load resistance value at the time of constant voltage and constant current switching;

[0035] Calculate the system operating frequency that satisfies the system pure resistance equal to the calculated first equivalent load;

[0036] Detect the real-time load resistance value and calculate the corresponding second equivalent load;

[0037] Judge the relationship between the first equivalent load and the second equivalent load. If the first equivalent load is not equal to the second equivalent load, adjust the system operating frequency to change the system pure resistance so that the system operates in the operating mode corresponding to the second equivalent load.

[0038] In a third aspect, the present invention provides a computer device, including a memory and a processor, where the memory stores a computer program, and when the processor executes the computer program, the steps of the method described above are implemented.

[0039] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method described above are implemented.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention proposes an electric field coupled wireless power transmission system and its control method. The designed electric field coupled wireless power transmission system can achieve seamless switching between constant current and constant voltage output modes, while maintaining a simple system structure, low cost, and high reliability. By adopting a symmetric resonant compensation circuit design, the system of the present invention can effectively reduce the magnetic field interference around the coupling mechanism, improve the transmission efficiency, and can transmit electric energy across metal obstacles. In addition, the system of the present invention causes less eddy current loss on metal conductors between or around the coupling mechanisms, so it is more suitable for applications in scenarios that require high flexibility and low interference. The control method of the present invention changes the pure resistive resistance by adjusting the system operating frequency, so as to achieve constant current or constant voltage output, without a complex control circuit or additional switching devices, simplifies the system design, reduces the cost, and improves the stability and reliability of the system.

[0041] In practical applications, an autonomous multiphase current-fed push-pull inverter with full resonance and zero voltage switch (ZVS) operation is symmetrically adopted at the transmitting end and the receiving end. This inverter eliminates the detection and control requirements of traditional converters, and can generate precise phase delays to achieve the autonomous full ZVS operation of the electric field coupled wireless power transmission system. The autonomous characteristic of this system is reflected in automatically tracking the frequency at which the voltage and current are in the same phase, and this frequency is the constant voltage and constant current switching point. Based on the constant voltage and constant current switching point, by adjusting the frequency of the inverter, that is, the operating frequency of the system, the constant current charging or constant voltage charging of the system, and the switching between the constant current charging and constant voltage charging of the system can be realized, without adding additional switching devices or requiring a complex control circuit, with high transmission efficiency and reliability. This design not only improves the flexibility and adaptability of the system, but also ensures efficient energy transmission and low electromagnetic interference characteristics, meeting the requirements of wireless power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0043] Figure 1 is the circuit block diagram of an electric field coupling wireless power transmission system provided by an embodiment of the present invention;

[0044] Figure 2 is the specific circuit diagram of an electric field coupling wireless power transmission system provided by an embodiment of the present invention;

[0045] Figure 3 is the specific circuit diagram of an autonomous multi-phase current-fed push-pull inverter provided by an embodiment of the present invention;

[0046] Figure 4 is provided by an embodiment of the present invention Figure 2 equivalent circuit diagram;

[0047] Figure 5 is the equivalent circuit diagram of the resonant network provided by an embodiment of the present invention;

[0048] Figure 6 is the frequency response characteristic curve diagram of the resonant network under the load values RL (i.e., R is 10, 50, 100 Ω) when the value of Cc is 1200p provided by an embodiment of the present invention;

[0049] Figure 7 is the frequency response characteristic curve diagram of the resonant network under the load values RL (i.e., R is 10, 50, 100 Ω) when the value of Cc is 200p provided by an embodiment of the present invention;

[0050] Figure 8 is the system working flow chart during the wireless charging of an unmanned aerial vehicle provided by an embodiment of the present invention;

[0051] Figure 9 is the current waveform diagram at the load end under the constant current working mode and with the change of the distance between the plates provided by an embodiment of the present invention;

[0052] Figure 10 is the current waveform diagram with the change of the load from 1 - 40 Ω when the distance between the plates is fixed (equivalent to 1200p) provided by an embodiment of the present invention;

[0053] Figure 11 is the voltage waveform diagram at the load end with the change of the distance between the plates when the load is 50 Ω under the constant voltage working mode provided by an embodiment of the present invention;

[0054] Figure 12It is a voltage waveform diagram at the load end when the load continues to change to a higher load starting from 50Ω provided by an embodiment of the present invention;

[0055] Figure 13 It is an internal structure diagram of a computer device for an electric field coupling wireless power transmission system and its control method provided by an embodiment of the present invention. Specific embodiments

[0056] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] Embodiment 1

[0058] Refer to Figures 1 - 13 , which is the first embodiment of the present invention. This embodiment provides an electric field coupling wireless power transmission system and its control method, including:

[0059] In the existing related technologies, there are some problems. For example, when traditional wireless power transmission systems achieve constant current or constant voltage output, they often require complex control circuits and additional switching devices, which not only increase the cost and volume of the system, but also affect the stability and reliability of the system. In addition, when these systems switch working modes, problems such as a decrease in efficiency and an increase in electromagnetic interference may occur.

[0060] This application provides a method that can effectively solve the above-mentioned problems. Next, multiple embodiments will be combined to elaborate in detail how to implement the design of this electric field coupling wireless power transmission system;

[0061] Figure 1 shows a circuit block diagram of an electric field coupling wireless power transmission system, including: a transmitting end and a receiving end;

[0062] In the embodiment of this application, the transmitting end at least includes a DC power supply, an inverter circuit, and a primary resonant compensation circuit;

[0063] The receiving end at least includes a secondary resonant compensation circuit designed for the primary resonant compensation circuit, a rectifier circuit, and a target load.

[0064] In an optional embodiment, the primary resonant compensation circuit and the secondary resonant compensation circuit can adopt the form of an LC series resonant circuit, where L represents an inductor and C represents a capacitor. This design can ensure that at a specific frequency, the impedance of the circuit is minimized, thereby improving the efficiency of energy transmission.

[0065] In an alternative embodiment, by precisely calculating and selecting appropriate inductance and capacitance values, resonance frequency matching with the transmitter and receiver can be achieved, thereby achieving the best energy transfer effect.

[0066] In an alternative embodiment, the primary resonance compensation circuit and the secondary resonance compensation circuit can also adopt the form of an LC parallel resonance circuit. The parallel resonance circuit can provide high impedance at a specific frequency, helping to reduce the energy loss of the system and allowing the system to operate stably within a wide frequency range.

[0067] In an alternative embodiment, by adjusting the values of the inductance and capacitance, the resonance frequency can be flexibly controlled to adapt to different working environments and requirements. This design not only optimizes the energy transfer efficiency but also improves the adaptability and robustness of the system.

[0068] It should be noted that the design of the resonance compensation circuit can also reduce the loss of the system and improve the overall transmission efficiency. In practical applications, this design can effectively reduce the problem of transmission efficiency decline caused by frequency offset and ensure the stable operation of the wireless power transmission system.

[0069] In the embodiment of the present application, the primary resonance compensation circuit includes a plurality of inductors and a plurality of capacitors;

[0070] The secondary resonance compensation circuit includes a plurality of inductors and a plurality of capacitors;

[0071] The secondary resonance compensation circuit is symmetrically arranged with the primary resonance compensation circuit.

[0072] In the embodiment of the present application, the primary resonance compensation circuit adopts an LCLC type compensation network. Since the secondary resonance compensation circuit is symmetrically arranged with the primary resonance compensation circuit, the secondary resonance compensation circuit also adopts an LCLC type compensation network.

[0073] Exemplarily, as Figure 2 shown, the primary resonance compensation circuit of this embodiment adopts an LCLC type compensation network, including capacitor C1, inductor L4, inductor L5, and capacitor C ex1 , both ends of capacitor C1 are connected to the two output terminals of the inverter circuit, both ends of inductor L5 are connected to the two output terminals of the inverter circuit, one end of inductor L4 is connected to one output terminal of the inverter circuit, and the other end of inductor L4 is connected to one end of capacitor C ex1 and the transmitting electrode plate P T1 (or P T3 ), the other end of capacitor C ex1 is connected to the transmitting electrode plate PT2 (or P T4 ) and the other output terminal of the inverter circuit. AsFigure 2 As shown, the secondary side resonance compensation circuit of this embodiment also adopts an LCLC type compensation network, which is symmetrically arranged with the primary side resonance compensation circuit.

[0074] In an alternative embodiment, the rectifier circuit and the inverter circuit can use the same switching elements to simplify the circuit design and reduce the manufacturing cost. The rectifier circuit is responsible for converting the alternating current output by the inverter circuit into direct current for use by the load.

[0075] In an alternative embodiment, the rectifier circuit can adopt a full-bridge rectifier structure, which can include four diodes or thyristor elements, and their connection method ensures efficient conversion of alternating current to direct current.

[0076] In an alternative embodiment, a filter circuit can be arranged between the rectifier circuit and the inverter circuit to reduce the ripple of the output voltage and improve the stability of power transmission.

[0077] In an alternative embodiment, the filter circuit is usually composed of an inductor and a capacitor, and their parameters are optimally selected according to the output frequency of the inverter circuit and the load characteristics. In this way, the electric field coupling wireless power transmission system can achieve efficient and stable energy transmission.

[0078] In another alternative embodiment, the inverter circuit and the rectifier circuit can also adopt an autonomous multi-phase current-fed push-pull inverter with full resonance and zero voltage switching (ZVS) operation;

[0079] In the embodiment of the present application, the inverter circuit includes a plurality of inductors, a plurality of capacitors, and a plurality of MOS transistors;

[0080] The rectifier circuit includes a plurality of inductors, a plurality of capacitors, and a plurality of MOS transistors;

[0081] The structures and parameters of the inverter circuit and the rectifier circuit are symmetrically arranged.

[0082] In the embodiment of the present application, as Figure 2 shown, the inverter circuit and the rectifier circuit adopt an autonomous multi-phase current-fed push-pull inverter with full resonance and zero voltage switching (ZVS) operation, and the structures and parameters are symmetrically arranged. The proposed inverter circuit uses exactly the same autonomous single-phase inverter with symmetric magnetic coupling to provide equal phase shifts to generate a magnetic field. This inverter eliminates the detection and control requirements of traditional converters and can generate precise phase delays to form an autonomous system with full ZVS operation.

[0083] Specifically, as Figure 3 shown, the autonomous multi-phase current-fed push-pull inverter includes inductor L 01 , inductor L 02 , inductor L03 , MOS transistor S 01 and MOS transistor S 02 , where one end of inductor L 01 is connected to one end of inductor L 02 and one end of inductor L 03 ; the other end of inductor L 02 is connected to the drain of MOS transistor S 01 ; the other end of inductor L 03 is connected to the drain of MOS transistor S 02 ; the sources of MOS transistors S 01 and S 02 are connected together as the first DC input terminal or the first DC output terminal; the other end of inductor L 01 is used as the second DC input terminal or the second DC output terminal; the common terminal of inductor L 02 and MOS transistor S01 is used as the first AC output terminal or the first AC input terminal; the common terminal of inductor L 03 and MOS transistor S 02 is used as the second AC output terminal or the second AC input terminal; when applied to the scenario of AC - to - DC conversion, the first DC input terminal and the second DC input terminal are respectively connected to the positive and negative poles of the DC power supply, and the first AC output terminal and the second AC output terminal are connected to the subsequent resonant circuit; when applied to the scenario of DC - to - AC conversion, the first AC input terminal and the second AC input terminal are connected to the previous resonant circuit, and the first DC output terminal and the second DC output terminal are respectively connected to both ends of the load.

[0084] In an alternative embodiment, as shown in Figure 2 , when this autonomous multi - phase current - fed push - pull inverter is used as an inverter circuit at the power transmission end (inductor L 01 , inductor L 02 , inductor L 03 , MOS transistor S 01 and MOS transistor S 02 are represented by inductor L1, inductor L2, inductor L3, MOS transistor S1 and MOS transistor S2 respectively), the first DC input terminal and the second DC input terminal are respectively connected to the positive and negative poles of DC power supply E dc , and the first AC output terminal and the second AC output terminal are connected to the primary - side resonant compensation circuit. When this autonomous multi - phase current - fed push - pull inverter is used as a rectifier circuit at the power reception end (inductor L 01 , inductor L 02 , inductor L 03 , MOS transistor S 01 and MOS transistor S 02 are represented by inductor L 10When represented by inductor L9, inductor L8, MOS transistor S4, and MOS transistor S3, the first AC input terminal and the second AC input terminal are connected to the secondary resonant compensation circuit, and the first DC output terminal and the second DC output terminal are respectively connected to both ends of load R L of load R L and a filter capacitor C is also connected in parallel across both ends of load R f .

[0085] It should be noted that the inverter circuit and the rectifier circuit using an autonomous multiphase current-fed push-pull inverter with full resonance and zero-voltage switching (ZVS) operation can significantly improve the power transmission efficiency and reduce energy losses. In addition, the full resonance operation ensures that the circuit operates near the resonance frequency, thereby reducing the voltage stress on the switching devices and extending the service life of the devices. The zero-voltage switching (ZVS) operation further reduces the power loss during the switching process because it allows the switching action to occur when the voltage is close to zero, thus reducing the switching loss. This design not only improves the overall performance of the system but also enhances the reliability of the system, making it more suitable for long-distance and high-efficiency wireless power transmission applications.

[0086] In the embodiments of the present application, the transmitting end and the receiving end include:

[0087] The transmitting end further includes a first transmitting plate and a second transmitting plate;

[0088] The receiving end further includes a first receiving plate and a second receiving plate;

[0089] The first transmitting plate, the second transmitting plate, the first receiving plate, and the second receiving plate constitute an electric field coupling mechanism.

[0090] In an alternative embodiment, there is provided an electric field-coupled wireless power transmission system with constant current and constant voltage output autonomy, and its circuit block diagram is as shown in Figure 1 and includes a transmitting end and a receiving end. The transmitting end includes a DC power supply, an inverter circuit, a primary resonant compensation circuit, and a pair of transmitting plates connected in sequence. The receiving end includes a pair of receiving plates, a secondary resonant compensation circuit, a rectifier circuit, and a load connected in sequence. The pair of transmitting plates and the pair of receiving plates constitute an electric field coupling mechanism.

[0091] In an alternative embodiment, in the high-frequency excitation part, the DC input voltage provided by the DC power supply is converted into high-frequency alternating current by a current-type inverter (usually a full-bridge inverter) and supplied to the subsequent circuit. The primary resonant compensation network realizes functions such as filtering, reactive power compensation, and voltage pumping to obtain a high-frequency excitation voltage, which is transmitted to the secondary resonant compensation circuit through the electric field coupling mechanism for resonant compensation, rectified and filtered by the rectifier, and finally a DC voltage is output to the load.

[0092] As an example of an application scenario, the electric field coupling wireless power transmission system of this embodiment is used for wireless charging of drones. Figure 2 The following shows the specific circuit diagram of the corresponding electric field coupling wireless power transmission system. The transmitting electrode plate pair consists of 2 transmitting electrode plates P T1 ~P T2 which are placed inside the four crossbars of the drone centering device. When the drone completes centering, there may be two situations: the receiving electrode plates are horizontally distributed or vertically distributed. The corresponding transmitting electrode plates are P T1 、P T2 (when horizontally distributed) and P T3 、P T4 (when vertically distributed). Therefore, the coupling capacitance can be ensured to be basically the same in both cases of the receiving electrode plate distribution.

[0093] In an alternative embodiment, to increase the coupling capacitance of the coupling mechanism to achieve high-power and efficient power transmission, the receiving end of the coupling mechanism is composed of two receiving electrode plates P R1 and P R2 formed by winding copper foil (aluminum foil) around the landing gear of the drone, which can achieve lightweight without changing the original shape of the drone.

[0094] In the embodiment of the present application, the first transmitting electrode plate and the second transmitting electrode plate are connected to the primary resonant compensation circuit;

[0095] The first receiving electrode plate and the second receiving electrode plate are connected to the secondary resonant compensation circuit;

[0096] The positive pole of the DC power supply is connected to the first DC input terminal, and the negative pole of the DC power supply is connected to the second DC input terminal;

[0097] Any one end of the target load is connected to the first DC output terminal, and the other end is connected to the second DC output terminal.

[0098] In the embodiment of the present application, the output of the inverter circuit is the first AC output terminal and the second AC output terminal, and the first AC output terminal and the second AC output terminal are connected to the primary resonant compensation circuit;

[0099] The input of the rectifier circuit is the first AC input terminal and the second AC input terminal, and the first AC input terminal and the second AC input terminal are connected to the secondary resonant compensation circuit.

[0100] In the embodiment of the present application, filter capacitors are connected in parallel at both ends of the target load.

[0101] In an alternative embodiment, the system can control the on and off of switches S1 and S2 through self-excitation characteristics to supply power to the transmitting electrode plates P T1 and PT2 A high-frequency excitation voltage is provided, and the automatic push-pull of the switching transistors S1 and S2 in the inverter circuit at the transmitting end always tracks the zero phase angle with a duty cycle of 50%. The corresponding two pairs of electrode plates generate "displacement current" under high-frequency high-voltage excitation, thereby realizing the transmission of electrical energy. The receiving-end LCLC compensation network realizes impedance matching, and the rectifier circuit converts the obtained high-frequency alternating current into direct current.

[0102] In an alternative embodiment, the system can achieve constant current and constant voltage outputs through frequency switching. At the constant current operating frequency, the system can achieve a constant current output; at the constant voltage operating frequency, the system can achieve a constant voltage output. By controlling the operating frequency of the system, smooth switching between the constant current and constant voltage modes can be achieved without the need for additional switching devices.

[0103] In an alternative embodiment, in control theory and automatic control systems, a linear autonomous system (also known as a linear autonomous differential equation system or a linear autonomous dynamic system) refers to a system whose dynamic behavior can be described by a system of linear differential equations, and the behavior of the system depends only on the system state and not on external inputs. An autonomous system means that the dynamic equations of the system do not explicitly depend on time, that is, the system can still evolve autonomously without external drive or input. The autonomous characteristic of this system is reflected in that it will automatically track the frequency f at which the voltage and current are in the same phase.

[0104] It should be noted that when the voltage and current are in the same phase, it means that the input impedance has no imaginary part. Therefore Figure 2 the circuit shown in Figure 4 can be finally equivalent to L_eq where R c is the equivalent load resistance, and its value is related to the equivalent capacitance C ESR of a pair of coupled electrode plates. R ESR is the equivalent pure resistive resistance, and its value is affected by the operating frequency f, but this effect is a high-order non-linear effect. In the constant voltage operating range, the value of R L_eq is very small and less than R L_eq . According to the KVL theorem, when the value of R ESR is much larger than R L_eq , the voltage across R L_eq is nearly constant. In the constant current operating region, the value of R ESR is less than R L_eq . According to the KCL theorem, when the value of R ESR is much smaller than R L_eq , the change in R

[0105] In the embodiments of the present application, the equivalent capacitances of the two pairs of coupled electrode plates are equal and both are C c , and the equivalent circuit of the corresponding coupling mechanism is as shown in Figure 5As shown, it constitutes a complete resonant network. Take the load value R L That is, R is 10, 50, 100 Ω, and the equivalent capacitance C of the plate c The values are 200 p and 1200 p, and through formula derivation, the frequency response characteristic curves of this resonant network are respectively Figure 6 and Figure 7 . Figure 6 and Figure 7 respectively show the gain amplitude and phase of the frequency response varying with frequency under different resistance values (R = 10 Ω, R = 50 Ω, R = 100 Ω) when C c is 1200 p and 200 p. Both the receiving end and the transmitting end use self-excited Push-pull inverters, and the parameters of the compensation network are symmetric. In the frequency range from 100 KHz to 10 MHz, the gain amplitude diagram shows frequency splitting, that is, two spikes appear in the high-frequency band. The phase response diagram shows multiple zero-crossing points, and these zero-crossing points correspond to the gain peak frequencies, indicating that zero phase angle (ZPA) can be achieved at these frequencies. These points are usually constant voltage or constant current points, suitable for self-excited resonant converter systems, and their equivalent impedance varies with frequency.

[0106] Definition:

[0107]

[0108] It should be noted that as long as the structures and parameters of the transmitting end and the receiving end are as symmetric as possible, and at the same time a is kept between 5 and 10, b is kept between 1 and 5, and a + b < 11, the above characteristics can be achieved.

[0109] In summary, the present invention proposes an electric field coupled wireless power transmission system. The designed electric field coupled wireless power transmission system can achieve seamless switching between constant current and constant voltage output modes, while keeping the system structure simple, low-cost, and highly reliable. By adopting a symmetric resonant compensation circuit design, the system of the present invention can effectively reduce the magnetic field interference around the coupling mechanism, improve the transmission efficiency, and can transmit electric energy across metal obstacles. In addition, the system of the present invention causes less eddy current loss on the metal conductors between or around the coupling mechanisms, so it is more suitable for applications in scenarios requiring high flexibility and low interference. The control method of the present invention changes the pure resistive resistance by adjusting the system operating frequency, so as to achieve constant current or constant voltage output, without complex control circuits or additional switching devices, simplifies the system design, reduces the cost, and improves the stability and reliability of the system.

[0110] In practical applications, an autonomous multi-phase current-fed push-pull inverter with full resonance and zero-voltage switching (ZVS) operation is symmetrically adopted at the transmitting end and the receiving end. This inverter eliminates the detection and control requirements of traditional converters and can generate precise phase delays to achieve the autonomous full-ZVS operation of the electric field-coupled wireless power transmission system. The autonomous characteristic of this system is reflected in that it can automatically track the frequency at which the voltage and current are in the same phase, which is the constant voltage and constant current switching point. Based on the constant voltage and constant current switching point, by adjusting the frequency of the inverter, that is, the operating frequency of the system, the constant current charging or constant voltage charging of the system can be achieved, as well as the switching between the constant current charging and constant voltage charging of the system, without the need to add additional switching devices or require complex control circuits. It has high transmission efficiency and reliability. This design not only improves the flexibility and adaptability of the system but also ensures efficient energy transmission and low electromagnetic interference characteristics, meeting the requirements of wireless power supply.

[0111] Embodiment 2

[0112] This embodiment also provides a control method for an electric field-coupled wireless power transmission system, including:

[0113] Determine the load resistance value at the time of constant voltage and constant current switching;

[0114] Calculate the corresponding first equivalent load according to the load resistance value at the time of constant voltage and constant current switching;

[0115] Calculate the operating frequency of the system that satisfies the pure resistive resistance of the system being equal to the calculated first equivalent load;

[0116] Detect the real-time load resistance value and calculate the corresponding second equivalent load;

[0117] Judge the relationship between the first equivalent load and the second equivalent load. If the first equivalent load is not equal to the second equivalent load, adjust the operating frequency of the system so that the pure resistive resistance of the system changes, and make the system operate in the operating mode corresponding to the second equivalent load.

[0118] This embodiment also provides a computer device, which can be a terminal, and its internal structure diagram can be as Figure 13As shown in the figure. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The communication interface of the computer device is used to communicate with external terminals in a wired or wireless manner, and the wireless manner can be implemented through WIFI, carrier network, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it realizes a control method for an electric field coupling wireless power transmission system. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball, or touchpad provided on the housing of the computer device, or an external keyboard, touchpad, or mouse, etc.

[0119] This embodiment also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0120] Determine the load resistance value during constant voltage and constant current switching;

[0121] Calculate the corresponding first equivalent load according to the load resistance value during constant voltage and constant current switching;

[0122] Calculate the system operating frequency that satisfies the condition that the pure resistive resistance of the system is equal to the calculated first equivalent load;

[0123] Detect the real-time load resistance value and calculate the corresponding second equivalent load;

[0124] Judge the relationship between the first equivalent load and the second equivalent load. If the first equivalent load is not equal to the second equivalent load, adjust the system operating frequency so that the pure resistive resistance of the system changes, and make the system operate in the operating mode corresponding to the second equivalent load.

[0125] Embodiment 3

[0126] In a preferred embodiment, taking the charging of an unmanned aerial vehicle (UAV) as an example, the method steps in the above embodiment are described. In the application of UAVs, lithium batteries are the main power source. However, the charging characteristics of lithium batteries require constant current charging at the initial stage of charging, and then switch to constant voltage charging when the voltage reaches a certain level. This charging curve requires the charging system to provide a constant current or voltage when the load changes. Existing charging systems usually require complex control circuits to achieve this function, while the constant current and constant voltage switching characteristics of the system of the present invention are similar to the lithium battery charging curve, with constant current when the load is small and constant voltage when the load is large. Without an additional control circuit, a relatively high coupling capacitance can be ensured to achieve efficient power transmission to meet the requirements.

[0127] Then, as Figure 8 shown in the flowchart, the corresponding system control process is as follows:

[0128] Determine the load resistance value R when switching from the constant voltage mode to the constant current mode or from the constant current mode to the constant voltage mode during UAV charging L ;

[0129] According to the load resistance value R L calculate the corresponding equivalent load R L_eq (constant voltage switching point);

[0130] Calculate the system operating frequency f that satisfies the system's pure resistive resistance R ESR equal to the calculated R L_eq ;

[0131] Detect the real-time load resistance value and calculate the corresponding equivalent load R L_eq1 ;

[0132] Judge the relationship between the equivalent load R L_eq1 and the equivalent load R L_eq . If R L_eq1 is less than R L_eq , it means that the load is small at this time and constant current charging is required. If R L_eq1 is greater than R L_eq , it means that the load is large at this time and constant voltage charging is required. If constant current charging is needed, adjust the system operating frequency f so that the system's pure resistive resistance R ESR is greater than R L_eq . If constant voltage charging is needed, adjust the system operating frequency f so that the system's pure resistive resistance R ESR is less than R L_eq .

[0133] If R L_eq1 is equal to R L_eq , the system can operate at the original system operating frequency f until the equivalent load of the system changes.

[0134] To verify the constant-current / constant-voltage output autonomous characteristics of the system, a = 6.73 and b = 3.33 are selected. As a comparison, Figure 2 a simulation model is built on the Ltspice simulation platform for the system circuit shown below for simulation. The current-source full-bridge inverter is composed of power MOSFETs S1 - S2. The rectifier part is the same as the transmitter circuit. The load end also consists of a filter capacitor Cf. The inverter part at the transmitter and the rectifier part at the receiver have the same structure. It can be seen that the system does not use any feedback control devices or microcontroller processors. The important parameters of the system are shown in Table 1.

[0135] Table 1 System Parameters

[0136]

[0137] In the simulation, the change in the plate distance is equivalent to the change in C c . Within a certain distance range, the larger the value of C c , the smaller the plate distance. The change range of C c is 200p - 1200p, and the plate distance is 0 - 5 cm. The load value for the constant-current to constant-voltage switching is 40 Ω.

[0138] In the constant-current working mode, the current waveform at the load end with the change in the plate distance is as shown in Figure 9 . Among them, when the plate distance is fixed (equivalent to 1200p), the current waveform with the load changing from 1 - 40 Ω is as shown in Figure 10 . The current remains almost within a certain range, indicating that the system can maintain the constant-current characteristic within a large range.

[0139] In the constant-voltage working mode, when the load is 50 Ω at this time, the voltage at the load end is almost constant with the change in the plate distance, and the waveform is as shown in Figure 11 . Among them, when the load continues to change to a higher load starting from 50 Ω, the voltage remains almost constant, as shown in Figure 12 , indicating that the system has strong robustness.

[0140] In summary, the constant-current and constant-voltage output autonomous electric-field-coupled wireless power transfer system provided by the embodiments of the present invention symmetrically adopts an autonomous multi-phase current-fed push-pull inverter with full resonance and zero-voltage switching (ZVS) operation at the transmitting end and the receiving end. This inverter eliminates the detection and control requirements of traditional converters and can generate precise phase delays to achieve the full-ZVS operation autonomy of the electric-field-coupled wireless power transfer system. The autonomous characteristic of this system is reflected in automatically tracking the frequency f at which the voltage and current are in the same phase. This frequency f is the constant-voltage and constant-current switching point. By adjusting the frequency of the inverter, that is, the operating frequency of the system, based on the constant-voltage and constant-current switching point, the constant-current charging or constant-voltage charging of the system can be achieved, as well as the switching between the constant-current charging and constant-voltage charging of the system, without the need to add additional switching devices or require complex control circuits. It has high transmission efficiency and reliability. This design not only improves the flexibility and adaptability of the system but also ensures efficient energy transfer and low electromagnetic interference characteristics, meeting the requirements of wireless power supply.

[0141] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

[0142] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present application can be implemented in various computer languages. For example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript.

[0143] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate for implementing in the process Figure 1One or more processes and / or blocks Figure 1 Apparatus for the functions specified in one or more blocks

[0144] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to work in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction apparatus that implements the functions in the process Figure 1 One or more processes and / or blocks Figure 1 The functions specified in one or more blocks

[0145] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, such that a series of operation steps are executed on the computer or other programmable apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions in the process Figure 1 One or more processes and / or blocks Figure 1 The steps of the functions specified in one or more blocks

[0146] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of the present application

[0147] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations

Claims

1. An electric field coupling wireless power transmission system, characterized in that, Comprising: A transmitting end and a receiving end; The transmitting end at least includes a DC power supply, an inverter circuit, and a primary resonant compensation circuit; The receiving end at least includes a secondary resonant compensation circuit designed for the primary resonant compensation circuit, a rectifier circuit, and a target load.

2. The electric field coupling wireless power transmission system according to claim 1, characterized in that Further comprising: The primary resonant compensation circuit includes a plurality of inductors and a plurality of capacitors; The secondary resonant compensation circuit includes a plurality of inductors and a plurality of capacitors; The secondary resonant compensation circuit is symmetrically arranged with the primary resonant compensation circuit.

3. The electric field coupling wireless power transmission system according to claim 2, wherein Further comprising: The inverter circuit includes a plurality of inductors, a plurality of capacitors, and a plurality of MOS transistors; The rectifier circuit includes a plurality of inductors, a plurality of capacitors, and a plurality of MOS transistors; The structures and parameters of the inverter circuit and the rectifier circuit are symmetrically arranged.

4. The electric field coupling wireless power transmission system according to claim 3, wherein The transmitting end and the receiving end include: The transmitting end further includes a first transmitting electrode plate and a second transmitting electrode plate; The receiving end further includes a first receiving electrode plate and a second receiving electrode plate; The first transmitting electrode plate, the second transmitting electrode plate, the first receiving electrode plate, and the second receiving electrode plate constitute an electric field coupling mechanism.

5. The electric field coupling wireless power transmission system according to claim 4, wherein Further comprising: The first transmitting electrode plate and the second transmitting electrode plate are connected to the primary resonant compensation circuit; The first receiving electrode plate and the second receiving electrode plate are connected to the secondary resonant compensation circuit; The positive pole of the DC power supply is connected to the first DC input terminal, and the negative pole of the DC power supply is connected to the second DC input terminal; Any one end of the target load is connected to the first DC output terminal, and the other end is connected to the second DC output terminal.

6. The electric field coupling wireless power transmission system according to claim 5, wherein Further comprising: The output of the inverter circuit is a first AC output terminal and a second AC output terminal, and the first AC output terminal and the second AC output terminal are connected to the primary resonant compensation circuit; The input of the rectifier circuit is a first AC input terminal and a second AC input terminal, and the first AC input terminal and the second AC input terminal are connected to the secondary resonant compensation circuit.

7. The electric field coupling wireless power transmission system according to claim 6, wherein Further comprising: Filtering capacitors are connected in parallel at both ends of the target load.

8. A control method for an electric field coupled wireless power transmission system, characterized in that, Comprising: Determine the load resistance value at the time of constant voltage and constant current switching; Calculate the corresponding first equivalent load according to the load resistance value at the time of constant voltage and constant current switching; Calculate the system operating frequency that satisfies the condition that the pure resistive resistance of the system is equal to the calculated first equivalent load; Detect the real-time load resistance value and calculate the corresponding second equivalent load; Judge the relationship between the first equivalent load and the second equivalent load. If the first equivalent load is not equal to the second equivalent load, adjust the system operating frequency so that the pure resistive resistance of the system changes, and make the system operate in the operating mode corresponding to the second equivalent load.

9. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method described in claim 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method described in claim 8.

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