Dual-mode excitation based on the pole omnidirectional quasi-static cavity resonant wireless power supply system

Abstract

This invention belongs to the field of wireless power transmission technology and discloses a poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation. Addressing the problems of existing technologies, such as the impact of the central pole structure on spatial integrity, uneven magnetic field distribution, and sensitivity to receiving angles, this system proposes a structural scheme including a transmitter, a cavity, and a receiver. The cavity employs a regular prism magnetically conductive cavity combined with a cavity compensation capacitor. The transmitting coil alternately excites the cavity in a dual-mode operation at a first and second frequency, and frequency switching creates a spatially uniform, direction-insensitive omnidirectional quasi-static composite magnetic field within the cavity. The receiving coil can efficiently receive power from any position within the cavity. This invention effectively improves space utilization and practicality, enhances magnetic field uniformity and angular robustness, and achieves high-precision modeling and optimization through parameter extraction methods, resulting in considerable transmission efficiency over most areas.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and in particular to a poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation. Background Technology

[0002] Wireless power transfer (WPT) technology, due to its safety and convenience, shows broad application prospects in fields such as implantable medical devices, drones, wearable devices, and electric vehicles. Achieving power transfer with high spatial degrees of freedom is a current research hotspot, aiming to fully demonstrate the convenience of WPT technology. Magnetic-coupled resonant WPT technology can achieve three-dimensional charging in a specific area by optimizing the magnetic coupling mechanism and control strategy. However, its uneven distribution of the excitation magnetic field limits the effective charging area, and the complex multi-sensor magnetic coupling system has high cost and limited robustness.

[0003] Quasi-static cavity resonant (QSCR) wireless power transfer technology is another promising solution. It enables the safe transfer of tens to hundreds of watts of power to portable electronic devices on a room-scale basis by exciting a quasi-static magnetic field within the resonant cavity. However, existing QSCR-WPT technologies have several limitations: First, the commonly used central pole structure disrupts the integrity of the internal space, affecting practicality and aesthetics; second, the fixed direction of the pulsating magnetic field excited within the cavity makes the receiving coil's performance highly sensitive to angular misalignment, lacking angular robustness; third, for complex cavity structures without poles, the surface current geometry is complex, making it difficult to establish an accurate equivalent circuit model and identify parameters, posing significant challenges to system design, optimization, and control.

[0004] Existing research, such as the patent application CN118300284A entitled "Cavity Resonant Wireless Power Transfer System for Three-Dimensional Omnidirectional Wireless Power Transfer", can achieve three-dimensional omnidirectional wireless power transfer by controlling the angular position of two driving coils and the phase of the excitation voltage on the two coils. However, it requires two driving coils, making the control relatively complex, and it does not analyze in detail the impact of changes in the load position on the system's transmission efficiency and capability. Summary of the Invention

[0005] This invention provides a poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation. The technical problem it solves is: how to provide a simple structure, no need for a central pole, uniform magnetic field distribution and excellent angular robustness all-space wireless power transmission system.

[0006] To address the above technical problems, this invention provides a poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation. The system includes a transmitter, a cavity, and a receiver. The transmitter has a transmitting coil. The cavity includes a regular prism magnetically conductive cavity and a cavity compensation capacitor embedded in the side opening of the cavity. The receiver has a receiving coil. The transmitting coil is positioned within the cavity to simultaneously adapt to a first frequency and a second frequency. The receiving coil is located at any position within the cavity. The switching frequency between the first and second frequencies satisfies the condition that the composite magnetic field within the cavity is a stable omnidirectional quasi-static field.

[0007] Preferably, at the first frequency, the magnetic field of the regular prism magnetic cavity is concentrated around the cavity wall; at the second frequency, the magnetic field of the regular prism magnetic cavity is polarized along the spatial diagonal direction.

[0008] Preferably, the bottom surface of the regular prism magnetic cavity is a regular N-gon, where N≥3; it can simultaneously accommodate the transmitting coils of the first frequency and the second frequency; and its position is close to the opening on one side of the regular prism magnetic cavity.

[0009] Preferably, the entire regular prism magnetic cavity is made of magnetic material, and the wall thickness is at least 5 times the skin depth of the magnetic material corresponding to the larger of the first and second frequencies.

[0010] Preferably, the cavity compensation capacitor is disposed on only one side opening, or disposed on two or more side openings; when disposed on two or more side openings, the cavity compensation capacitor is the equivalent capacitance formed by the capacitors embedded on all sides.

[0011] Preferably, the transmitting end includes a DC power supply, a high-frequency inverter, a transmitting end resonant network, and the transmitting coil connected in sequence; the receiving end includes the receiving coil, the receiving end resonant network, a rectifier circuit, and a load connected in sequence.

[0012] Preferably, the equivalent parameter L at the first frequency PI R PI M PT1 M TS1 and the equivalent parameter L at the second frequency DMPI R DMPI M PT2 M TS2 Both are extracted based on reflection impedance and simulated annealing algorithms. PI L DMPIR represents the equivalent inductance of the regular prism magnetic cavity at the first frequency and the second frequency, respectively. PI R DMPI The internal resistances M of the prism magnetically permeable cavity at the first frequency and the second frequency, respectively. PT1 M PT2 M represents the mutual inductance between the transmitting coil and the regular prism magnetic cavity at the first frequency and the second frequency, respectively. TS1 M TS2 These refer to the mutual inductance between the regular prism magnetic cavity and the receiving coil at the first frequency and the second frequency, respectively.

[0013] Preferably, the parameter L is obtained. DMPI R DMPI M PT2 M TS2 The specific steps are as follows:

[0014] S1. Build a simulation system to measure the input impedance-frequency response curve and output impedance-frequency response curve of the magnetic field concentrated around the cavity wall of the regular prism magnetic cavity.

[0015] S2. Based on the reflection impedance theory, establish the input impedance equation and the output impedance equation. Based on the circuit resonance relationship, derive L from the input impedance equation and the output impedance equation. DMPI R DMPI M PT2 and M TS2 The value is used as the initial value;

[0016] S3. Employing simulated annealing algorithm, based on L... DMPI R DMPI M PT2 and M TS2 Optimization is performed within the search boundary set by the initial value to obtain L. DMPI R DMPI M PT2 and M TS2 The optimal value.

[0017] Preferably, step S2 specifically includes the following steps:

[0018] S21. Establish the input impedance equation based on the reflection impedance theory;

[0019] S22. Select the second frequency ω based on the input impedance-frequency response curve. DMPI The corresponding reference point N1 and the reference point N2 corresponding to another frequency, ω DMPI That is, the angular frequency corresponding to the highest real part resistance;

[0020] S23. Solve for the equivalent inductance L of the cavity based on the resonance relationship.DMPI ;

[0021] S24. Connect the reference points N1, N2 and the cavity equivalent inductance L. DMPI Substituting into the input impedance equation, the equivalent resistance R of the cavity is obtained by solving. DMPI ;

[0022] S25, Based on the cavity equivalent resistance R DMPI Using the resistance R2 and reactance X2 measured at point N2, the coupling coefficient k between the cavity and the transmitting coil can be calculated. PT2 ;

[0023] S26, Based on coupling coefficient k PT2 Mutual inductance M PT2 The relationship is obtained by M. PT2 ;

[0024] S27. Based on the same process as steps S21 to S26, and based on the output impedance-frequency response curve and the output impedance equation, we obtain M. TS2 .

[0025] Preferably, in step S3, the objective function of the simulated annealing algorithm is defined as the root mean square error between the theoretical impedance curve and the measured impedance curve.

[0026] This invention provides a poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation. It employs a design of a centrally located, upright prism-shaped magnetically conductive cavity. An opening on the cavity's side is used to embed a lumped capacitor, serving as a series compensation capacitor. A transmitting coil is then placed inside the cavity near one of the side openings for magnetic field excitation. The cavity receives the magnetic field driven by the transmitting coil and converts it into electrical energy. This electrical energy is then converted into an RLC circuit through the surface current of the cavity wall and the compensation capacitor, exciting both PI and DMPI operating modes. These two modes work together to eliminate magnetic field dead zones, forming a uniform composite magnetic field throughout the cavity. A receiving coil positioned anywhere within the cavity receives the quasi-static magnetic field and converts the magnetic energy into electrical energy through resonance. After rectification, this electrical energy powers the load. Furthermore, the system optimizes its operating frequency using a cavity equivalent parameter extraction method based on reflection impedance analysis and simulated annealing algorithms, ensuring stable power transmission under different load locations and receiving angles.

[0027] The beneficial effects of this invention include: the QSCR system proposed in this invention eliminates the central pole, improving space utilization and practicality; the QSCR system proposed in this invention significantly improves the spatial uniformity and angular insensitivity of the intracavity magnetic field through dual-mode excitation; the parameter extraction method provided in this invention can effectively overcome the influence of processing errors and parasitic parameters, achieving high-precision modeling and optimized design of the system; the system can achieve a transmission efficiency of over 40% in most areas, making it suitable for providing full-space wireless power supply for IoT devices, etc. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the DPI-WPT system provided in an embodiment of the present invention;

[0029] Figure 2 This is a circuit topology diagram of the DPI-WPT system provided in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the structure and parameters of the regular prism magnetically conductive cavity provided in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the current direction and magnetic field strength in DMPI mode and PI mode provided in the embodiments of the present invention;

[0032] Figure 5 This is a graph showing the variation of the average excitation magnetic field strength inside the cavity when the transmitting coil is at different positions and angles, as provided in an embodiment of the present invention.

[0033] Figure 6 This is a flowchart of parameter extraction provided in an embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of the impedance frequency response curve extracted from port 1 provided in an embodiment of the present invention;

[0035] Figure 8 This is a comparison chart of the measurement and extraction curves of the impedance frequency response of the DPI-WPT system provided in the embodiments of the present invention;

[0036] Figure 9 This is the excitation magnetic field distribution diagram (Z=0) under single-mode and dual-mode provided in the embodiment of the present invention.

[0037] Figure 10 This is a schematic diagram of the selected measurement position provided in an embodiment of the present invention;

[0038] Figure 11 This is a graph showing the change in the magnetic field along the Z-axis provided in an embodiment of the present invention;

[0039] Figure 12This is an efficiency diagram of receiving coils located at different positions and at different angles under different modes provided in the embodiments of the present invention;

[0040] Figure 13 This is a comparison chart of the theoretical and experimental efficiency of the DPI-WPT system provided in this embodiment of the invention;

[0041] Figure 14 This is a comparison chart of efficiency radar graphs for DMPI mode, PI mode, and dual mode provided in the embodiments of the present invention. Detailed Implementation

[0042] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0043] The poleless omnidirectional quasi-static cavity resonant wireless power supply system (DPI-WPT system) based on dual-mode excitation provided in this invention is composed as follows: Figure 1 As shown, it includes a transmitter, a cavity, and a receiver. The transmitter includes a DC power supply (U) connected in sequence. C ), high-frequency inverter (a full-bridge inverter composed of MOSFETs S1 to S4), transmitter resonant network and transmitter coil L P The cavity end includes a regular prism magnetically conductive cavity and a cavity compensation capacitor embedded in the side opening of the regular prism magnetically conductive cavity. The receiving end includes a receiving coil L connected in sequence. S The receiver resonant network, rectifier circuit (a full-bridge rectifier composed of diodes D1 to D4), and load (R) L The excitation frequency of the high-frequency inverter is at the first frequency (f). PI ) and second frequency (f DMPI Switching between ) and transmitting coil L P The receiving coil is positioned arbitrarily within a prism-shaped magnetically permeable cavity, adaptable to both the first and second frequencies. At the first frequency, the magnetic field of the cavity is concentrated around the cavity walls; this operating mode is called the PI mode. At the second frequency, the magnetic field is polarized along the diagonal direction of space; this operating mode is called the DMPI mode. The switching frequency between the first and second frequencies satisfies the condition that the combined magnetic field within the prism-shaped magnetically permeable cavity is a stable omnidirectional quasi-static field.

[0044] As an example, both the transmitter compensation network and the receiver compensation network use series compensation. The transmitter compensation network uses a series compensation method with the transmitter coil L. P Series-connected emitter compensation capacitor C PThe receiving end compensation network adopts the same as the receiving coil L S Series-connected receiver compensation capacitor C S Specifically, in order to adapt to the first and second frequencies, achieve system resonance at each frequency, and realize high-efficiency wireless transmission, the transmitter compensation network switches to a configuration that is synchronized with the transmitting coil L when the high-frequency inverter switches to the first frequency. P The compensation network of the first transmitter resonating at the first frequency switches to a state similar to that of the transmitter coil L when the high-frequency inverter switches to the second frequency. P The second transmitter compensation network resonates at the second frequency. Similarly, the receiver compensation network switches to a state resonant with the receiving coil L when the high-frequency inverter switches to the first frequency. S The compensation network of the first receiver resonating at the first frequency switches to a state similar to that of the receiving coil L when the high-frequency inverter switches to the second frequency. S The compensation network for the second receiver resonates at the second frequency.

[0045] Figure 1 The equivalent circuit of the system shown is as follows Figure 2 As shown. Figure 2 Middle,U I R is the AC source equivalent to the DC power supply and the high-frequency inverter. eq For rectifier circuit and load R L For the equivalent AC load, L PI L DMPI M represents the equivalent inductance of the prism magnetically permeable cavity at the first and second frequencies, respectively. PT1 M PT2 The transmitting coils L are respectively at the first frequency and the second frequency. P Mutual inductance between the magnetically permeable cavity and the regular prism, M TS1 M TS2 The first and second frequencies are respectively the positive prism magnetic cavity and the receiving coil L. S Mutual intuition between them, U O For AC output voltage, R P R T R S The transmitting coil L is respectively P 1. Regular prism magnetic cavity, 2. Receiving coil L S The equivalent internal resistance, C T This is the cavity compensation capacitor. In the analysis below, the transmitter compensation capacitor C at the first and second frequencies... P Use C respectively P1 and C P2 This indicates the receiving end compensation capacitor C at the first and second frequencies. S Use C respectively S1 and C S2 This indicates that R at the first frequency and the second frequencyT Use R respectively PI R DMPI express.

[0046] The base of the prism-shaped magnetically permeable cavity is a regular N-gon, where N ≥ 3. It can simultaneously accommodate transmitting coils L at both the first and second frequencies. P The location is near an opening on one side of the regular prism magnetically permeable cavity. The cavity compensation capacitor can be placed on only one side opening or on two or more side openings. When placed on two or more side openings, the cavity compensation capacitor is the equivalent capacitance formed by the capacitors embedded on all sides. The side openings simulate doors and windows in an actual room and reduce communication shielding; the opening position, size, shape, and other parameters are set according to actual needs. The regular prism magnetically permeable cavity is entirely made of magnetically permeable material, and the wall thickness is at least five times the skin depth of the magnetically permeable material corresponding to the larger of the first and second frequencies. The first and second frequencies are optimized in the 500kHz-700kHz range.

[0047] As a preferred embodiment, the bottom surface of the regular prism magnetic cavity is a regular hexagon, as shown in the three-dimensional diagram below. Figure 3 As shown, the regular prism magnetic cavity is a non-closed hexahedral cavity made of aluminum alloy. Its length (overall width of the base) is denoted as l, its width (side length of the base) as w, and its height as h. It has large openings on its four side walls, with an opening height of h1. The cavity wall thickness is T. Multiple lumped-surface capacitors are uniformly embedded on specific edges at the connection points between the upper and lower parts of the cavity openings, forming a cavity resonant capacitor C1. This cavity structure is equivalent to a relay coil, and all the distributed capacitors together are equivalent to a resonant capacitor connected to L. T Series relay resonant capacitor C T The transmitting and receiving coils are double-layered stacked square coils with identical parameters. The outer side length of each layer is D, the inner side length is d, and the total number of turns is N.

[0048] The working principle of this system is as follows: the high-frequency inverter excites the transmitting coil L P An alternating magnetic field is generated. Because the drive coil is carefully positioned to simultaneously and efficiently excite both PI and DMPI modes, its magnetic field couples to the metal cavity, inducing corresponding currents. The current directions and magnetic field strengths for the PI and DMPI modes are as follows: Figure 4 As shown, Figure 4 (a) Corresponds to DMPI mode. Figure 4 (b) Corresponding to PI mode. For example... Figure 4 As shown in (a), the current in the DMPI mode flows approximately parallel to the top surface of the cavity, and its main magnetic field component is polarized along the spatial diagonal. Figure 4As shown in (b), the current path in the PI mode forms a closed loop, and its magnetic field strength is mainly concentrated around the cavity wall. By controlling the rapid switching between these two modes (the lower the switching frequency, the better, without affecting the effect), the magnetic fields generated by these two modes are superimposed within the cavity, forming a composite magnetic field with a highly uniform spatial distribution and insensitive directionality. The receiving coil L is located inside the cavity. S The magnetic field lines that cut the composite magnetic field generate an induced electromotive force, and the electrical energy is supplied to the load after passing through the receiving end compensation network and rectification and filtering.

[0049] In this embodiment, the position and angle of the drive coil are crucial to ensure efficient and stable excitation of the dual modes. Figure 5 The simulation analysis demonstrates the average magnetic field strength within the cavity that the drive coil can excite at different test points and angles. The test points are located at distances of 5 cm, 10 cm, and 15 cm from the edge of the opening, and the test angles range from 0° to 180° with respect to the side. In the simulation, the parameters of the regular prism magnetically permeable cavity and the transceiver coil are shown in Table 1. The PI mode and DMPI mode are set to 625 kHz and 516 kHz respectively, with a switching frequency of 100 Hz for both modes.

[0050] Table 1: Parameters of the regular prism magnetic cavity and transceiver coil

[0051]

[0052] Figure 5 Simulation results show that placing the transmitting coil 5 cm from the edge of the opening achieves the best magnetic field excitation effect. This is not an arbitrary choice, but rather based on a comprehensive consideration of edge effects and coupling strength. According to electromagnetic field theory, a distance that is too close (<5 cm) will cause the transmitting coil to be in the turbulent edge field at the cavity opening, inducing strong eddy current losses on the metal cavity wall and reducing the system's Q value; while a distance that is too far will lead to insufficient mutual inductance. Therefore, 5 cm is the optimal engineering position to balance coupling efficiency and suppress edge eddy current losses, and this position can ensure effective excitation of the required DMPI and PI modes. Due to the complex geometry of the current on the wall of the electrodeless cylinder cavity, it is difficult to directly derive its equivalent circuit. This invention equates it to a circuit as follows: Figure 2 The three-coil model shown ignores the direct coupling between the transmitting and receiving coils. The cavity end is represented by two parallel RLC branches, corresponding to the PI mode (L... PI , R PI ) and DMPI mode (L DMPI ,R DMPI The equivalent parameters of ). To accurately obtain these equivalent parameters (L) PI , L DMPI , R PI , R DMPIM PT1 M PT2 M TS1 M TS2 To calculate theoretical efficiency, this invention proposes an equivalent parameter extraction method based on reflection impedance and simulated annealing algorithm. The process is as follows: Figure 6 .

[0053] The parameter acquisition process is the same for both modes. Taking DMPI mode as an example, the parameter L is acquired... DMPI R DMPI M PT2 M TS2 The specific steps are as follows:

[0054] S1. Build a simulation system and use a vector network analyzer (VNA) to measure the input impedance-frequency response curve and output impedance-frequency response curve of the magnetic field concentrated around the cavity wall of the regular prism magnetic cavity.

[0055] S2. Based on the reflection impedance theory, establish the input impedance equation and the output impedance equation. Based on the circuit resonance relationship, the input impedance equation, and the output impedance equation, derive L. DMPI R DMPI M PT2 and M TS2 The value is used as the initial value;

[0056] S3. Using simulated annealing algorithm, in L DMPI R DMPI M PT2 and M TS2 Optimize within the search boundary to obtain L DMPI R DMPI M PT2 and M TS2 The optimal value.

[0057] In step S1, the input impedance-frequency response curve is as follows: Figure 7 As shown, where For frequency ω equals ω DMPI At, ω DMPI This represents the angular frequency corresponding to the second frequency. According to reflection impedance theory, when the excitation frequency approaches the natural resonant frequency of the cavity mode, the system resonates strongly due to the extremely small equivalent internal resistance of the cavity, causing a sharp increase in the real part of the impedance reflected to the source. Therefore, the peak point of the input impedance real part curve accurately corresponds to the resonant frequency of the system in DMPI mode, where the energy coupling from the emitter to the cavity is most efficient. The output impedance-frequency response curve and... Figure 7 similar.

[0058] refer to Figure 6 Step S2 specifically includes the following steps:

[0059] S21. Establish the input impedance equation based on the reflection impedance theory;

[0060] S22. Select ω based on the input impedance-frequency response curve. DMPI The corresponding reference point N1 and the reference point N2 corresponding to another frequency;

[0061] S23. Solve for the equivalent inductance L of the cavity based on the resonance relationship. DMPI ;

[0062] S24. Connect the reference points N1, N2 and the cavity equivalent inductance L. DMPI Substituting into the input impedance equation, the equivalent resistance R of the cavity is obtained by solving. DMPI ;

[0063] S25, Based on the cavity equivalent resistance R DMPI Using the resistance R2 and reactance X2 measured at point N2, the coupling coefficient k between the cavity and the transmitting coil can be calculated. PT2 ;

[0064] S26, Based on coupling coefficient k PT2 Mutual inductance M PT2 The relationship is obtained by M. PT2 ;

[0065] S27. Based on the same process as steps S21 to S26, and based on the output impedance-frequency response curve and the output impedance equation, we obtain M. TS2 .

[0066] To obtain M PT2 For example, in step S21, based on the reflection impedance theory, the system's input impedance equation is derived as follows:

[0067] (1)

[0068] Where R represents the input resistance (real part) and X represents the input reactance (imaginary part).

[0069] based on Figure 2 The equivalent circuit shown can be obtained as follows:

[0070] (2)

[0071] In step S22, the two selected reference points N1 correspond to (ω=ω1=ω DMPI N1 and N2 correspond to (ω=ω2). The resistances measured at reference points N1 and N2 are denoted as R1 and R2, respectively.

[0072] In step S23, according to the definition of resonance, the capacitance C T Through inductor L DMPI Represented as:

[0073] (3)

[0074] In step S24, equation (3) is substituted into equation (2), and the dependent variable C is eliminated by substitution. T ,get:

[0075] (4)

[0076] Wherein, the coupling coefficient k between the cavity and the transmitting coil PT2 and R DMPI For unknown reasons, R P L P C P and resonant angular frequency ω DMPI All of these can be obtained through measurement. Next, the coupling coefficient k needs to be solved using the N2 point on the input impedance-frequency response curve. PT2 With resistance R DMPI .

[0077] In step S25, at point N2 (ω=ω2), the imaginary part of the input impedance is X2, and the real part is R2. Simplifying equation (2), the resistance R can be derived. DMPI The expression is as follows:

[0078] (5)

[0079] In step S26, by solving equations (4) and (5) simultaneously, the coupling coefficient k can be derived. PT2 The expression is as follows:

[0080] (6)

[0081] To describe the reflection impedance between the drive coil and the resonant cavity, the mutual inductance M needs to be calculated. PT2 By utilizing the relationship between the coupling coefficient and mutual inductance, the mutual inductance M can be obtained. PT2 The expression is as follows:

[0082] (7)

[0083] Through steps S21-S26 above, using two characteristic reference points (N1, N2) on the impedance curve, L is analytically calculated. DMPI R DMPI M PT2 Although these parameters have measurement errors, their numerical magnitudes are accurate and will be used as the initial search values ​​for the simulated annealing algorithm in subsequent step S3. For M... TS2 Then, based on the same steps S21~S26, the output impedance-frequency response curve, output impedance equation, and resonance relationship are calculated.

[0084] Step S3 specifically includes the following steps:

[0085] L DMPI R DMPI M PT2 and M TS2 The boundary is determined by the upper and lower limits that the system can reach, and is the global search range. In this example, L DMPI R DMPI M PT2 and M TS2 The search boundaries are set as follows:

[0086] (8)

[0087] The objective function of the simulated annealing algorithm is defined as the root mean square error between the theoretical impedance curve and the measured impedance curve. Examples of the finally extracted equivalent circuit parameters are shown in Table 2.

[0088] Table 2: System Resonance Parameters

[0089]

[0090] Figure 8 The comparison between the optimized theoretical impedance curve and the measured curve is shown. Figure 8 Figures (a), (b), (c), and (d) show the equivalent circuit diagram of the transmitter coupling, the frequency response comparison curve of the input impedance at port 1, the equivalent circuit diagram of the receiver coupling, and the frequency response comparison curve of the input impedance at port 2, respectively. Figure 8 It can be seen that the theoretical and measured curves of the input impedance frequency response of the AC input port (Port1) and the AC output port (Port2) are in high agreement, which verifies the correctness and effectiveness of the equivalent circuit model and parameter extraction method.

[0091] This embodiment uses electromagnetic field simulation software to analyze the magnetic field characteristics of the system. Figure 9 This is the excitation magnetic field distribution diagram (Z=0) under single-mode and dual-mode conditions provided in the embodiments of the present invention. Figure 9 In the diagram, (a), (b), and (c) correspond to the single DMPI mode, the single PI mode, and the dual mode, respectively. Figure 9 It is clearly shown that the magnetic field distribution in the single mode has obvious directionality and non-uniformity, while the composite magnetic field generated by the dual-mode cooperative operation exhibits excellent uniformity across the entire cavity cross section (Z=0 plane).

[0092] To verify the angular robustness, nine representative locations were selected within the cavity, such as... Figure 10As shown, the receiving coil was rotated from 0° to 180° at each position, and its transmission efficiency was measured. The magnetic field variation curves along the Z-axis at different positions are shown below. Figure 11 As shown. Figure 11 This further indicates that the magnetic field distribution in most areas along the cavity height direction (Z-axis) remains relatively stable.

[0093] Figure 12 It shows the efficiency of receiving coils located in different positions under different modes at different angles. Figure 12 In the diagram, (a), (b), and (c) correspond to the single DMPI mode, the single PI mode, and the dual mode, respectively. Figure 12 The results show that in single-mode, the transmission efficiency varies drastically with angle. However, in dual-mode, the efficiency curve flattens out, and the variation decreases significantly. To quantify the angle robustness of the DPI-WPT system, the Field Uniformity Index (FUI) is introduced. According to the international standard IEEE Std C95.3-2021, its calculation formula is as follows:

[0094] (9)

[0095] Where, σ η The standard deviation of transmission efficiency This is the arithmetic mean of the transmission efficiency.

[0096] (10)

[0097] In equation (10), N represents the number of sample data points. Calculations using equations (9) and (10) show that the FUI under dual-mode is significantly lower than that under single-mode, proving that the system of this invention has excellent angle insensitivity.

[0098] Finally, an experimental platform was built to verify the system. The system impedance characteristics were measured using a vector network analyzer, and the equivalent circuit parameters were obtained using the parameter extraction method described above. Subsequently, a power amplifier was used as the source, with a load R... L The transmission efficiency of the system at different positions and angles under a current of 50Ω.

[0099] Figure 13 The detailed characteristics of how the system's transmission efficiency varies with distance are demonstrated. Figure 13 In (a) and (b), respectively, along... Figure 10 The efficiency variation curves of paths n1 and n2. For example... Figure 13 As shown in (a), along the n1 path (mainly the DMPI mode-dominated region), the experimental measurements closely follow the theoretical curve, indicating that the system can maintain high efficiency even during long-distance transmission. Figure 13As shown in (b), on the n2 path (crossing the mode switching zone), the single PI mode is less efficient at short distances, while the single DMPI mode is less efficient at long distances. However, the dual-mode system can operate along the envelope of the two curves through automatic switching. Figure 13 The experimental results confirm that the dual-mode excitation strategy effectively overcomes the distance limitation of the single mode, ensuring efficient and stable power transmission throughout the entire transmission path.

[0100] Figure 14 The system was tested at nine typical locations within the cavity. Figure 10 The omnidirectional transmission efficiency radar charts for positions 1-9 in the cavity are shown in (a)-(i), which correspond to the test results (efficiency above 40%) for positions 1 to 9 in the cavity, respectively. Yellow area (DMPI): represents the coverage range of a single DMPI mode; green area (PI): represents the efficiency coverage range of a single PI mode; red dashed box (dual mode): represents the actual efficiency envelope of the dual-mode system of this invention. Figure 14 The experimental results show that the system achieves a transmission efficiency of over 40% in most areas of the cavity under dual-mode conditions, and maintains good performance at different angles.

[0101] In summary, the poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation provided by the embodiments of the present invention effectively solves the problems of central pole, angle sensitivity and modeling difficulties in traditional QSCR systems, and realizes high-efficiency power transmission in all space and all directions, providing a practical solution for future all-space wireless charging.

[0102] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation, characterized in that: The device includes a transmitter, a cavity, and a receiver. The transmitter is equipped with a transmitting coil. The cavity includes a regular prism magnetically conductive cavity and a cavity compensation capacitor embedded in the side opening of the regular prism magnetically conductive cavity. The receiver is equipped with a receiving coil. The transmitting coil is placed in the regular prism magnetically conductive cavity at a position that can simultaneously adapt to a first frequency and a second frequency. The receiving coil is located at any position in the regular prism magnetically conductive cavity. The switching frequency between the first frequency and the second frequency satisfies the condition that the composite magnetic field inside the regular prism magnetically conductive cavity is a stable omnidirectional quasi-static field. At the first frequency, the magnetic field of the regular prism magnetic cavity is concentrated around the cavity wall; at the second frequency, the magnetic field of the regular prism magnetic cavity is polarized along the spatial diagonal direction; the equivalent parameters at the first frequency... L PI , R PI , M PT1 , M TS1 and equivalent parameters at the second frequency L DMPI , R DMPI , M PT2 , M TS2 Extraction is based on reflection impedance and simulated annealing algorithms. L PI , L DMPI These are the inductances equivalent to the magnetically permeable prism cavity at the first frequency and the second frequency, respectively. R PI , R DMPI These are the internal resistances of the positive prism magnetically conductive cavity at the first frequency and the second frequency, respectively. M PT1 , M PT2 These refer to the mutual inductance between the transmitting coil and the regular prism magnetically conductive cavity at the first frequency and the second frequency, respectively. M TS1 , M TS2 These refer to the mutual inductance between the regular prism magnetically conductive cavity and the receiving coil at the first frequency and the second frequency, respectively. Get parameters L DMPI , R DMPI , M PT2 , M TS2 The specific steps are as follows: S1. Build a simulation system to measure the input impedance-frequency response curve and output impedance-frequency response curve of the magnetic field concentrated around the cavity wall of the regular prism magnetic cavity. S2. Based on the reflection impedance theory, establish the input impedance equation and the output impedance equation. Based on the circuit resonance relationship, derive the input impedance equation and the output impedance equation. L DMPI , R DMPI , M PT2 and M TS2 The value is used as the initial value; S3. Employing simulated annealing algorithm, based on... L DMPI , R DMPI , M PT2 and M TS2 Optimization is performed within the search boundary set by the initial value, resulting in... L DMPI , R DMPI , M PT2 and M TS2 The optimal value.

2. The poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation according to claim 1, characterized in that: The bottom surface of the regular prism magnetic cavity is a regular N-gon, where N≥3; the position of the transmitting coil that can simultaneously adapt to the first frequency and the second frequency is close to the opening on one side of the regular prism magnetic cavity.

3. The poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation according to claim 2, characterized in that: The entire regular prism magnetic cavity is made of magnetic material, and the wall thickness is at least 5 times the skin depth of the magnetic material corresponding to the larger of the first and second frequencies.

4. The poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation according to claim 3, characterized in that: The cavity compensation capacitor may be disposed on only one side opening or on two or more side openings; when disposed on two or more side openings, the cavity compensation capacitor is the equivalent capacitance formed by the capacitors embedded on all sides.

5. The poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation according to claim 4, characterized in that: The transmitting end includes a DC power supply, a high-frequency inverter, a transmitting end resonant network, and the transmitting coil connected in sequence; the receiving end includes the receiving coil, the receiving end resonant network, a rectifier circuit, and a load connected in sequence.

6. The poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation according to claim 1, characterized in that, Step S2 specifically includes the following steps: S21. Establish the input impedance equation based on the reflection impedance theory; S22. Select the second frequency based on the input impedance-frequency response curve. ω DMPI The corresponding reference point N 1 and the reference point corresponding to another frequency N 2, ω DMPI That is, the angular frequency corresponding to the highest real part resistance; S23. Solve based on the resonance relationship. L DMPI ; S24, Reference point N 1. N 2 and L DMPI Substituting into the input impedance equation, we obtain the solution. R DMPI ; S25, based on R DMPI and N Resistance measured at 2 points R 2 and reactance X 2. Calculate the coupling coefficient between the regular prism magnetic cavity and the transmitting coil. k PT2 ; S26, Based on Coupling Coefficient k PT2 Mutual induction M PT2 The relationship, to obtain M PT2 ; S27. Based on the same process as steps S21 to S26, and based on the output impedance-frequency response curve and the output impedance equation, we obtain... M TS2 .

7. The poleless omnidirectional quasi-static cavity resonant wireless power supply system based on dual-mode excitation according to claim 1, characterized in that, In step S3, the objective function of the simulated annealing algorithm is defined as the root mean square error between the theoretical impedance curve and the measured impedance curve.

Images