Wireless power transmission system based on impedance self-adjustment and efficiency improvement method thereof

Abstract

The invention discloses a wireless electric energy transmission system based on impedance self-adjustment and an efficiency improvement method thereof, and belongs to the technical field of wireless electric energy transmission. The system comprises a DC voltage source, an inversion module, a primary side compensation network, an integrated coupling mechanism, a secondary side compensation network, a rectification module, a filter capacitor and a load. The integrated coupling mechanism integrates the primary side compensation inductor, the secondary side compensation inductor and the coupling coil into a whole to form a self-adjusting variable inductor changing along with an air gap. Then, based on a second-generation non-dominated sorting genetic algorithm, multi-objective optimization is carried out on compensation capacitance and input voltage, and optimal parameters are determined under detuning degree constraint by taking minimization of output voltage fluctuation and total loss of the system as objectives; constant voltage output is achieved through phase shift control, and all-working-condition zero-voltage switching is achieved. The device does not need additional variable impedance elements, has the advantages of being simple in structure, stable in control, high in efficiency, high in air gap fluctuation resistance and the like, and is suitable for air gap dynamic change scenes such as wireless charging of automatic guided vehicles and electric vehicles.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission technology, specifically relating to a wireless power transmission system based on impedance self-adjustment and its efficiency improvement method, which is particularly suitable for wireless power supply scenarios with dynamic changes in air gap. Background Technology

[0002] Wireless power transfer technology (WPT) has been widely used in fields such as industrial automation, biomedicine, transportation, and consumer electronics due to its advantages such as no physical contact, safety and convenience, and strong environmental adaptability. It has become a core solution to address the safety hazards and lack of flexibility of traditional wired power supply.

[0003] In practical applications, the coupling mechanism of WPT systems often faces air gap variation issues due to fluctuations in operating conditions, such as the air gap changes caused by load variations in Automated Guided Vehicles (AGVs). Due to the influence of the ferrite core, the self-inductance and mutual inductance of the coupling coils change with the air gap, which disrupts the system's resonant state, increasing system output ripple and reducing system efficiency. Since system efficiency and output ripple are key performance indicators of wireless power transfer systems, addressing this issue is crucial.

[0004] To maintain the resonant state of a WPT system under different air gaps, the following methods are commonly used: First, impedance matching, using variable impedance components (such as capacitor matrices, switched capacitors, variable inductors, and cascaded transformer step-down circuits) to counteract the circuit loop detuning caused by changes in coupling parameters in the WPT system; however, this adds extra components and increases system complexity and cost. Second, frequency conversion, controlling the converter frequency to maintain the system's resonant state in real time to ensure efficiency under different operating conditions; however, it cannot solve the problem of simultaneous primary and secondary detuning, and frequent modulation of the controller can lead to unstable regulation. Third, based on the inherent characteristics of a specific compensation topology, primary / secondary resonance is achieved by using a hybrid compensation topology or a switching compensation topology; this method has limited adaptability and increases system design complexity and cost.

[0005] Therefore, there is an urgent need for a wireless power transmission scheme that can automatically adjust impedance under air gap changes, maintain system resonance, improve transmission efficiency, and has a simple structure. Summary of the Invention

[0006] The purpose of this invention is to provide a wireless power transmission system based on impedance self-adjustment and its efficiency improvement method to solve the problems of system detuning and efficiency reduction caused by air gap changes, and to achieve efficient and stable power transmission over a wide air gap and a wide load range.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a wireless power transmission system based on impedance self-adjustment, the system comprising a DC power supply, an inverter module, a primary-side compensation network, an integrated coupling mechanism, a secondary-side compensation network, a rectifier module, a filter capacitor, and a load.

[0008] The inverter module is a full-bridge inverter, connected between the DC voltage source and the primary-side compensation network. Both the primary-side and secondary-side compensation networks are LCC-type compensation networks, each including a compensation capacitor and a compensation inductor connected in series. The integrated coupling mechanism consists of a primary-side coupling coil, a secondary-side coupling coil, and compensation inductors located in the primary-side compensation network and the secondary-side compensation network, respectively. The primary-side and secondary-side coupling coils are unipolar Q-type coils; the compensation inductors in the primary-side compensation network are bipolar DD-type coils; and the compensation inductors in the secondary-side compensation network are tic-tac-toe coils with opposite current directions in adjacent coil windings. There is no cross-coupling between the primary-side coupling coil, the secondary-side coupling coil, the compensation inductors in the primary-side compensation network, and the compensation inductors in the secondary-side compensation network. The primary-side coupling coil and the compensation inductors in the primary-side compensation network are integrated into one unit, and the secondary-side coupling coil and the compensation inductors in the secondary-side compensation network are also integrated into one unit. The inductance values ​​of both the primary-side and secondary-side compensation inductors adaptively change with the air gap, achieving primary-side input impedance adjustment and secondary-side detuning suppression. The rectifier module is a full-bridge rectifier, connected between the secondary compensation network and the filter capacitor; the filter capacitor is connected in parallel with the load.

[0009] Secondly, the present invention provides a method for improving the efficiency of a wireless power transmission system based on impedance self-adjustment. This method can improve the efficiency of the aforementioned wireless power transmission system. The method includes: Obtain and determine the operating parameters of the wireless power transmission system, including operating frequency, rated output voltage, load variation range, and mutual inductance / self-inductance variation range; Based on the second-generation non-dominated sorting genetic algorithm, with the optimization objectives of minimizing system output voltage fluctuation and minimizing system total loss, under the preset primary-side detuning degree and secondary-side detuning degree constraints, the compensation capacitor parameters of the primary-side compensation network and the secondary-side compensation network, as well as the input voltage of the DC voltage source, are optimized to obtain the optimal system parameters. The system is configured according to the optimal system parameters, and phase-shift control is implemented on the inverter module to achieve precise adjustment of the output voltage and to achieve zero-voltage switching under all operating conditions.

[0010] The primary-side detuning and secondary-side detuning are defined by the primary-side equivalent impedance angle and the secondary-side equivalent impedance angle, respectively; the optimization objective function is a multi-objective function that simultaneously considers output voltage fluctuations and total system losses.

[0011] Objective function: in, This indicates system output voltage fluctuation. This represents the total power loss of the system. This represents the compensation capacitance of the primary-side compensation network. This represents the compensation capacitor of the secondary side compensation network. Indicates the system input voltage. Indicates the degree of detuning of the original side. Indicates the degree of detuning of the secondary side. Indicates the air gap height of the integrated coupling mechanism. This indicates the load value.

[0012] The total system losses include inverter switching losses, coil internal resistance losses, and rectifier conduction losses; when the system achieves zero-voltage switching, the inverter switching losses are minimized.

[0013] The optimization steps based on the second-generation non-dominated sorting genetic algorithm include: The fitting relationship between the self-inductance and mutual inductance of each inductor in the integrated coupling mechanism and the air gap was obtained by electromagnetic field simulation. Set the number of algorithm iterations and the total number of particles, and perform multi-objective optimization within the parameter constraint space; Select the system parameters that satisfy the detuning constraint from the obtained Pareto optimal solution set as the optimal solution.

[0014] The phase-shift control includes: adjusting the phase difference between the upper and lower bridge arms of the inverter module to control the fundamental amplitude of the output voltage; ensuring that the inverter output current lags behind the output voltage, maintaining zero-voltage switching conditions across the entire operating range. Specifically, it involves adjusting the conduction angle of the inverter bridge arm switching transistors to achieve precise constant voltage output from the system; and coordinating with the dynamic impedance adjustment of the primary-side compensating inductor in the integrated coupling mechanism to meet the constraint conditions of wide-range zero-voltage switching on the primary side, thereby reducing switching losses.

[0015] Thirdly, the present invention provides a device comprising the aforementioned wireless power transmission system for achieving efficient and stable wireless power transmission in scenarios with dynamic changes in the air gap. The device is a wireless power supply system for automated guided vehicles, electric vehicles, industrial robots, or medical devices.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) By integrating the compensation inductor and the coupling coil into a single design, the additional components such as variable capacitors, adjustable inductors, or switch arrays required by traditional impedance matching schemes are eliminated, reducing material costs and assembly complexity, and improving system reliability. In addition, the impedance self-adjustment is achieved by utilizing the natural change in inductance value caused by the change in air gap, eliminating the need for external sensors and complex drive circuits, further simplifying the system control structure.

[0017] (2) The integrated variable inductor automatically adjusts the compensation parameters according to the air gap change, so that the system maintains an approximately resonant state throughout the entire operating range, effectively suppressing the efficiency drop caused by detuning. Experimental results show that under dynamic operating conditions with an air gap of 30~60mm and a load of 40~60Ω, the DC-DC efficiency of the system remains stable between 92.6% and 94.23%. At the same time, wide-range zero-voltage switching is achieved through the coordinated adjustment of primary impedance and phase-shift control, which reduces inverter switching losses and improves the overall system efficiency.

[0018] (3) The second-generation non-dominated sorting genetic algorithm is used to optimize the system compensation parameters and input voltage for multiple objectives. Under the condition that real-time phase shift control is not required, the system reduces the output voltage fluctuation in a wide air gap and a wide load range. The integrated decoupling coil structure avoids cross-coupling interference and improves the system's anti-disturbance capability and operational stability under dynamic air gap. It is suitable for various application scenarios with air gap fluctuations, such as automated guided vehicles, wireless charging of electric vehicles, and industrial robots.

[0019] (4) By obtaining the globally optimal system parameters through multi-objective optimization, the complexity of the real-time control algorithm is reduced. Based on the optimized parameters, only a small-amplitude phase shift control is needed to achieve precise adjustment of the output voltage. The control modulation depth is small and the dynamic response is fast, which reduces the requirements for the controller performance and is conducive to the low-cost implementation and promotion of the system.

[0020] (5) The overall transmission efficiency of the system is still very high in the non-resonant state. The use of decoupled integrated coils not only saves space for the system, but also eliminates the cross coupling between the coupling coil and the compensation inductor, and between the compensation inductors, reducing the complexity of system analysis and design. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a wireless power transmission circuit.

[0022] Figure 2 This is a schematic diagram of the integrated coupling mechanism.

[0023] Figure 3 The diagram shows the variation of self-inductance and mutual inductance of the integrated coupling mechanism with air gap height.

[0024] Figure 4This is a flowchart of the efficiency improvement method of the present invention.

[0025] Figure 5 This is a diagram showing the Pareto front results of the NSGA-Ⅱ algorithm of this invention.

[0026] Figure 6 Waveform diagram for achieving zero-voltage switching in an inverter.

[0027] Figure 7 The waveform diagram is shown in the system experiment.

[0028] Figure 8 The figure shows the experimental results of primary and secondary side detuning.

[0029] Figure 9 The figure shows the experimental results of system efficiency. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] like Figure 1 As shown in the figure, this embodiment discloses a wireless power transmission system based on impedance self-adjustment. The system includes a DC power supply Vdc, a full-bridge inverter, a primary-side compensation network, an integrated coupling mechanism, a secondary-side compensation network, a full-bridge rectifier, a filter capacitor C0, and a load R.

[0032] The full-bridge inverter uses a full-bridge inverter circuit composed of four MOS switches Q1, Q2, Q3, and Q4. The four MOS switches form two bridge arms. By adjusting the conduction angle of the switches in the bridge arms, the system can achieve precise constant voltage output.

[0033] The primary-side compensation network is an LCC-type compensation network, including a primary-side compensation capacitor C. P1 C P2 Primary-side compensating inductor L P1 The equivalent internal resistance R of the coil P R P1 The secondary compensation network is also an LCC-type compensation network, including secondary compensation capacitors C. S1 C S2 Primary-side compensating inductor L S1 The equivalent internal resistance R of the coil S R S1 .

[0034] like Figure 2 As shown, the integrated coupling mechanism consists of a primary-side compensating inductor L P1 Secondary compensation inductor L S1 Coupled with primary side coil L PSecondary coupling coil L S The structure is designed with decoupling between each coil, and the primary-side coupled coil L... P and secondary coupling coil L S It is a unipolar Q-type coil, and the primary-side compensating inductance L P1 It is a bipolar DD-type coil; the secondary compensation inductor L S1 The coils are in a grid pattern, with the currents in adjacent square coils flowing in opposite directions; the primary-side coupling coil L P Secondary coupling coil L S Primary-side compensating inductor L P1 and secondary compensation inductor L S1 There is no cross coupling between them, and the primary and secondary compensation inductors and coupling coils are integrated into one unit.

[0035] The full-bridge rectifier circuit is composed of four diodes D1, D2, D3, and D4.

[0036] The DC voltage source is connected to the input terminal of the full-bridge inverter, and the output terminal of the full-bridge inverter is sequentially connected to the primary-side compensation network and the primary-side coupling coil L of the integrated coupling mechanism. P The secondary coupling coil L of the integrated coupling mechanism S Connect the secondary compensation network, full-bridge rectifier, and filter capacitor C in sequence. O and load R.

[0037] Due to the presence of the magnetic core, changes in the air gap alter the coil parameters (self-inductance and mutual inductance), leading to system detuning and consequently reducing system efficiency and output characteristics. This embodiment employs an LCC-LCC compensation topology, utilizing the aforementioned characteristics to integrate the primary / secondary compensation inductors with the primary / secondary coupled coils, resulting in two variable inductors. The compensation inductance values ​​self-adjust as the air gap changes to reduce secondary detuning; while the variable compensation inductor on the primary side can adjust the input impedance to offset the efficiency loss caused by air gap variations.

[0038] Since changes in the air gap will cause changes in the self-inductance and mutual inductance of the coupled coils, and the secondary inductance is a key component of the secondary compensation network, changes in the secondary inductance will directly change the secondary detuning degree. Therefore, the influence of air gap changes on the secondary compensation network can be offset by dynamically adjusting the secondary inductance, thereby reducing the secondary detuning degree and suppressing detuning.

[0039] Based on Kirchhoff's voltage law, the loop voltage equations for the LCC-LCC topology are as follows: In the formula, the system angular frequency , Indicates the system's operating frequency. This indicates the output current of the full-bridge inverter. Indicates the primary input current. Indicates the secondary output current. This indicates the system output current.

[0040] The system output voltage is obtained from the above formula. Output current in, According to Thevenin's theorem, the secondary impedance is... in Indicates the secondary resistance. This represents the secondary-side reactance. The degree of detuning on the secondary side... Then calculate the primary current. Between and secondary current phase angle

[0041]

[0042] System communication - communication side efficiency: and These are the internal resistances of the primary-side coupling coil and the secondary-side coupling coil, respectively.

[0043] Communication-communication efficiency is determined by Secondary side mistuning Degree determines, as Increase It shows a monotonically decreasing trend. Therefore, to make maximize, Ideally, it should approach zero, which means the system's secondary side is in resonance.

[0044] Air gap fluctuations cause changes in the self-inductance and mutual inductance of the coupling coils, directly disrupting the primary impedance characteristics. If the primary impedance cannot adapt to these changes, primary detuning will occur. Therefore, the integrated coupling mechanism in this embodiment changes the system impedance through primary-side compensation inductance, thereby reducing efficiency loss.

[0045] impedance reflected from the secondary side to the primary side Primary impedance , indicating the equivalent load on the primary side. Indicates the primary-side equivalent reactance;

[0046] Detuning of the primary side Input impedance angle

[0047] This embodiment utilizes phase-shift control of a full-bridge inverter to achieve precise constant voltage output, while also achieving zero-voltage switching (ZVS) throughout the process. Precise constant voltage output is achieved by adjusting the conduction angle of the bridge arm switches in the full-bridge inverter; the primary-side compensation inductor L in the integrated coupling mechanism... P1 Dynamic impedance regulation and parameter optimization are used to meet the constraints of wide-range zero-voltage switching on the primary side and reduce switching losses.

[0048] Phase-shift control refers to the complementary gate drive signals with a 50% duty cycle on the same bridge arm at the operating frequency. To prevent shoot-through short circuits on the same bridge arm, a dead time is introduced. δ d Furthermore, a phase difference is introduced between switching transistors Q1 and Q4 (as well as Q2 and Q3) to generate a conduction angle of... α Quasi-square wave voltage V i .

[0049] Root mean square value of the fundamental output voltage of a full-bridge inverter in, α This indicates the conduction angle of the full-bridge inverter. It can be adjusted... α It can be adjusted V i The fundamental frequency component is used to meet the output voltage requirements under varying mutual inductance, self-inductance, and load conditions.

[0050] For phase-shift control, zero-voltage switching (ZVS) should be used to reduce the switching losses of the MOSFETs. The output current of the full-bridge inverter... I i It should lag behind its output voltage. V i Furthermore, in order to minimize reactive current in the circuit, it must be limited to a reasonable range.

[0051] Detuning of the primary side in, This represents the phase angle difference between the output voltage and the fundamental voltage of the full-bridge inverter. This represents the phase angle difference between the output current and the fundamental voltage of the full-bridge inverter.

[0052] This embodiment optimizes parameters based on the second-generation non-dominated sorting genetic algorithm NSGA-II. The decision variables of the NSGA-II algorithm include the compensation capacitance of the original edge compensation network. C P1 , C P2 The compensation capacitor of the secondary side compensation network C S1 , C S2 Input voltage of DC power supply Vdc Compensation capacitor parameters and input DC voltage It must be within a reasonable range.

[0053] Since the output voltage fluctuation is calculated by integrating the fluctuations within the system's operating range when the air gap height changes: in, Indicates the system output voltage. This is the rated output voltage. For the range of mutual inductance changes, It is the range of load variation under constant voltage mode.

[0054] The total system losses include the losses of the full-bridge inverter, coupling coils, and full-bridge rectifier, among which the power losses of the full-bridge inverter are the largest. P Inverter Conduction loss of MOS switch P CLM Diode conduction loss P CLD and diode switching losses P SLMD Composition. Zero-voltage switching of MOS switches reduces or even eliminates the conduction losses of MOS switches. When achieving zero-voltage switching, the compensation topology parameters should make the primary-side impedance of the system inductive within the operating range to minimize the power consumption of the full-bridge inverter.

[0055] MOS switch conduction loss Diode conduction loss

[0056] Diode switching losses

[0057] Where is the drain-source on-resistance of the MOS switch, is the output current of the full-bridge inverter, is the inverter phase shift angle; is the diode gate voltage, is the diode on-resistance; and is the system operating frequency. θ This represents the phase difference between the inverter's output voltage and output current. t r The rise time of the MOSFET. t f This refers to the fall time of the MOSFET. In this embodiment, the MOSFET model is C2M0080120, and its... r DS =80mΩ, r D =119.4mΩ, t r =22ns, t f =14ns.

[0058] The power loss of a full-bridge rectifier originates from the forward voltage drop of the rectifier diodes and filter capacitors; Full-bridge rectifier power loss in, This is the forward voltage of the diode. The diode is the equivalent on-resistance. In this embodiment, the diode is model SBR10U45SP5Q. V F =1.6V, r CF =7.1mΩ.

[0059] The power loss of passive components mainly originates from the internal resistance of the coil; capacitance loss is negligible, and the power loss of the coupling coil is also a factor.

[0060] In summary, the total power loss of the system Calculated by integrating the power loss within the system's operating range:

[0061] The system optimization objective function is:

[0062] This embodiment uses the operating frequency. f 85kHz, rated output voltage V N It is 96V, and the load variation range is [40Ω, 60Ω]; such as Figure 3 As shown, when the air gap changes from 30mm to 60mm, the self-inductance of the primary-side coupled coil... L P Variation range [124.9μH, 140.6μH], self-inductance of secondary coupled coil L S Variation range [120.3 μH, 140.9 μH], mutual inductance M Variation range [50.3μH, 91μH], primary-side compensation inductance L S1 Variation range [80.3μH, 94.33μH], secondary side compensation inductance L P1 Variation range [82.2 μH, 91.8 μH].

[0063] The total number of iterations and the total number of particles in the second-generation non-dominated sorting genetic algorithm are determined to obtain the design variables. C P1 , C P2 , C S1 ,C S2 ,and V dc The subspace range is determined; then the system compensation parameters are optimized using a second-generation non-dominated sorting genetic algorithm.

[0064] The steps of the NSGA-II algorithm mentioned in this embodiment are as follows: First, determine the total number of iterations T and the total number of particles N of the second-generation non-dominated sorting genetic algorithm NSGA-II. Then, by constraining the compensation parameters and the input voltage, obtain the design variables (primary-side compensation capacitor). C P1 , C P2 Secondary side compensation capacitor C S1 , C S2 DC input voltage V dc The subspace range of ) is then determined; then, using a second-generation non-dominated sorting genetic algorithm, the optimization objectives are "minimizing the output voltage fluctuation under all operating conditions without phase shift control" and "minimizing the total system loss under all operating conditions," combined with the primary side detuning degree. α P ∈(0 ° [40°], secondary side detuning α S Under the constraint condition ∈ [87°, 94°], the system compensation parameters and DC input voltage are optimized. The system parameters optimized by the NSGA-Ⅱ algorithm reduce the control modulation depth, and precise output is achieved through phase shift control, enabling stable operation without complex control circuits.

[0065] like Figure 4 As shown, the second-generation non-dominated sorting genetic algorithm used in this invention is used for compensation parameter optimization. The specific steps are as follows: Step 1: Obtain f , V dc , α Pmin , α Pmax , α Smin ,、 α Smax , V N Values ​​were determined, and the structure and dimensions of the integrated coupling mechanism were specified. Step 2: Set the number of turns of the coupling coil and the compensating inductor, i.e. N 1min ≤N 1 ≤N 1max , N 2min ≤N2 ≤N 2max ; Step 3: Simulate the coupling mechanism in the electromagnetic field simulation software MAXWELL to obtain... L P , L P1 , L S1 , L S , M and N The data, and fitting L P , L P1 , L S1 , L S , M and h The relationship between them; Step 4: Optimize the compensation parameters using the NSGA-II algorithm; Step 5: Select system parameters that satisfy the detuning constraint within the Pareto optimal solution set; the Pareto front plot of the NSGA-II algorithm, as shown below. Figure 7 As shown.

[0066] Step 6: Check if the conditions are met. α Pmin ≤ α P ≤ α Pmax and α Smin ≤ α S ≤ α Smax ; Step 6.1: If the requirements of Step 6 are met, the parameter is acceptable; if not, check if... N 2 ≤N 2max ; Step 6.2: If the requirements of Step 6.1 are met, return to Step 3; if not, check if... N 1 ≤N 1max ; Step 6.3: If the requirements of 6.2 are met, return to step 3; if not, adjust the structure and dimensions of the integrated coupling mechanism.

[0067] Based on the Pareto front, a suitable solution can be selected by balancing the system output voltage fluctuation and system losses under no-phase-shift control. In this embodiment, the selected solution parameters are as follows: C P1=35.24nF C P2 =90.14nF C S1 =76nF C S2 =39nF、 V dc =175V.

[0068] The results show that, Figure 6 As shown, under simple phase-shift control, zero-voltage switching is achieved on the primary side across all operating conditions and a wide range; as Figure 7 , Figure 8 As shown, the secondary side detuning is maintained between [87°, 94°], and the primary side detuning is between (0, 40°]. Figure 9 The system efficiency was demonstrated; under all load and altitude conditions, the proposed method achieved experimental efficiency between 92.6% and 94.23%. The proposed method... h =50mm, R The highest efficiency of 94.23% is achieved at 50Ω. h =30mm, R The minimum efficiency of 92.6% is achieved at 55Ω. This verifies that the proposed design enables the system to achieve high efficiency under air gap variations.

[0069] This embodiment achieves adaptive impedance adjustment and efficiency improvement of the wireless power transmission system under air gap changes by integrating variable inductor design and intelligent optimization control. It has the advantages of simple structure, stable control and high efficiency, and is suitable for dynamic air gap application scenarios such as AGV and wireless charging of electric vehicles.

[0070] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A wireless power transfer system based on impedance self-adjustment, characterized in that: It includes a DC power supply, inverter module, primary-side compensation network, integrated coupling mechanism, secondary-side compensation network, rectifier module, filter capacitor and load; The inverter module is a full-bridge inverter, connected between the DC voltage source and the primary-side compensation network. Both the primary-side and secondary-side compensation networks are LCC-type compensation networks, each including a series-parallel compensation capacitor and a compensation inductor. The integrated coupling mechanism consists of a primary-side coupling coil, a secondary-side coupling coil, and compensation inductors located in the primary-side compensation network and the secondary-side compensation network, respectively. The primary-side and secondary-side coupling coils are unipolar Q-type coils; the compensation inductors in the primary-side compensation network are bipolar DD-type coils; and the compensation inductors in the secondary-side compensation network are tic-tac-toe coils with opposite current directions in adjacent coil windings. There is no cross-coupling between the primary-side coupling coil, the secondary-side coupling coil, the compensation inductors in the primary-side compensation network, and the compensation inductors in the secondary-side compensation network. The primary-side coupling coil and the compensation inductors in the primary-side compensation network are integrated into one unit, and the secondary-side coupling coil and the compensation inductors in the secondary-side compensation network are also integrated into one unit. The inductance values ​​of both the primary-side and secondary-side compensation inductors adaptively change with the air gap, achieving primary-side input impedance adjustment and secondary-side detuning suppression. The rectifier module is a full-bridge rectifier, connected between the secondary compensation network and the filter capacitor; the filter capacitor is connected in parallel with the load.

2. A method for improving the efficiency of a wireless power transfer system based on impedance self-adjustment, characterized in that, Applied to the wireless power transmission system of claim 1, the method includes the following steps: Determine the operating parameters of the wireless power transmission system, including operating frequency, rated output voltage, load variation range, and mutual inductance / self-inductance variation range; Based on the second-generation non-dominated sorting genetic algorithm, with the optimization objectives of minimizing system output voltage fluctuation and minimizing system total loss, under the preset primary-side detuning degree and secondary-side detuning degree constraints, the compensation capacitor parameters of the primary-side compensation network and the secondary-side compensation network, as well as the input voltage of the DC voltage source, are optimized to obtain the optimal system parameters. The system is configured according to the optimal system parameters, and phase-shift control is implemented on the inverter module to achieve precise adjustment of the output voltage and to achieve zero-voltage switching under all operating conditions.

3. The method for improving the efficiency of a wireless power transmission system based on impedance self-adjustment according to claim 2, characterized in that, The primary-side detuning and secondary-side detuning are defined by the primary-side equivalent impedance angle and the secondary-side equivalent impedance angle, respectively. The optimization objective function is a multi-objective function, simultaneously considering output voltage fluctuations and total system power loss; Objective function: in, This indicates system output voltage fluctuation. This represents the total power loss of the system. This represents the compensation capacitance of the primary-side compensation network. This represents the compensation capacitor of the secondary side compensation network. Indicates the system input voltage. Indicates the degree of detuning of the original side. Indicates the degree of detuning of the secondary side. Indicates the air gap height of the integrated coupling mechanism. This indicates the load value.

4. The method for improving the efficiency of a wireless power transmission system based on impedance self-adjustment according to claim 3, characterized in that, The total system losses include inverter switching losses, coil internal resistance losses, and rectifier conduction losses; when the system achieves zero-voltage switching, the inverter switching losses are minimized.

5. The method for improving the efficiency of a wireless power transmission system based on impedance self-adjustment according to claim 3, characterized in that, The optimization steps based on the second-generation non-dominated sorting genetic algorithm include: The fitting relationship between the self-inductance and mutual inductance of each inductor in the integrated coupling mechanism and the air gap was obtained by electromagnetic field simulation. Set the number of algorithm iterations and the total number of particles, and perform multi-objective optimization within the parameter constraint space; Select the system parameters that satisfy the detuning constraint from the obtained Pareto optimal solution set as the optimal solution.

6. The method for improving the efficiency of a wireless power transmission system based on impedance self-adjustment according to claim 2, characterized in that, The phase shift control includes: adjusting the phase difference between the upper and lower bridge arms of the full bridge in the inverter module to control the fundamental amplitude of the output voltage; ensuring that the inverter output current lags behind the output voltage, and maintaining zero-voltage switching conditions throughout the entire operating range.

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