A method for estimating parameters of a wireless power transfer system

Abstract

The present application relates to a kind of wireless power transmission system parameter estimation method, belong to wireless power transmission technical field, solve the problem of insufficient precision of parameter estimation method calculation complexity.It comprises: the output voltage and output current of primary side transmitting end inverter are collected;Based on the output voltage and output current, the voltage of transmitting parallel compensation capacitor two sides and the current of transmitting coil are calculated;According to the voltage of transmitting parallel compensation capacitor and the current of transmitting coil, the equivalent input impedance of primary side transmitting end is calculated;Based on the tangent value of equivalent input impedance decoupling calculation secondary side receiving end complex impedance, according to the tangent value of secondary side receiving end complex impedance, the load parameter of secondary side receiving end and the mutual inductance parameter between transmitting coil and receiving coil are calculated;Based on equivalent input impedance and the tangent value of secondary side receiving end complex impedance, the transmission efficiency of wireless power transmission system is estimated, based on transmission efficiency and load parameter, the load characteristic of wireless power transmission system is estimated.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and in particular to a method for estimating parameters of a wireless power transmission system. Background Technology

[0002] Wireless power transfer technology enables contactless power transmission via electromagnetic coupling and has wide applications in electric vehicles, mobile device charging, and medical implants. Its core lies in parameter matching between the primary transmitter and secondary receiver, including coil inductance, load characteristics, and system efficiency, all of which directly affect transmission performance.

[0003] Existing methods for estimating parameters of wireless power transmission systems have the following shortcomings. On the one hand, traditional parameter estimation methods often rely on complex mathematical modeling, requiring precise knowledge of the system's internal structure and parameters, which is difficult to obtain in practical applications, thus limiting the feasibility and accuracy of parameter estimation. Existing technologies require precise measurement of parameters such as the size, shape, and relative position of the transmitting and receiving coils before further calculations can be performed, but these parameters may not be accurately obtained in real-world scenarios due to environmental factors or equipment limitations.

[0004] Existing methods typically involve the coupling of multiple variables during the calculation process, resulting in cumbersome calculations and low accuracy. When estimating the load parameters of the secondary receiver and the mutual inductance parameters between the transmitting and receiving coils, the traditional decoupling methods are ineffective due to the mutual influence between these parameters, thus affecting the accuracy of the overall system parameter estimation and making it difficult to meet the requirements for high-precision parameter estimation in practical applications. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a method for estimating parameters of a wireless power transmission system, in order to solve the problems of computational complexity and insufficient accuracy of existing parameter estimation methods.

[0006] On one hand, embodiments of the present invention provide a method for estimating parameters of a wireless power transmission system, comprising the following steps:

[0007] S1. Collect the output voltage and output current of the primary-side transmitter inverter;

[0008] S2. Based on the output voltage and output current, calculate the voltage across the parallel compensation capacitor and the current in the transmitting coil.

[0009] S3. Calculate the equivalent input impedance of the primary-side transmitter based on the voltage of the parallel compensation capacitor and the current of the transmitter coil.

[0010] S4. Calculate the tangent of the complex impedance of the secondary receiving end based on the equivalent input impedance decoupling. Calculate the load parameters of the secondary receiving end and the mutual inductance parameters between the transmitting coil and the receiving coil based on the tangent of the complex impedance of the secondary receiving end.

[0011] S5. Estimate the transmission efficiency of the wireless power transmission system based on the tangent of the equivalent input impedance and the complex impedance of the secondary receiving end. Estimate the load characteristics of the wireless power transmission system based on the transmission efficiency and load parameters.

[0012] As a further improvement to this application, the calculation of the tangent value of the complex impedance at the secondary receiving end based on the equivalent input impedance decoupling includes:

[0013] The equivalent input impedance is converted into a complex form. Based on the real and imaginary parts of the equivalent input impedance, combined with the self-inductance of the transmitting coil, the internal resistance of the primary transmitting end, and the compensation capacitor, the tangent value of the complex impedance of the secondary receiving end is decoupled and calculated.

[0014] As a further improvement of this application, the equivalent input impedance is converted into a complex form. Based on the real and imaginary parts of the equivalent input impedance, combined with the self-inductance of the transmitting coil, the internal resistance of the primary transmitting end and the compensation capacitor, the tangent value of the complex impedance of the secondary receiving end is decoupled and calculated as shown in the calculation formula (1).

[0015]

[0016] Where k is the tangent of the complex impedance at the secondary receiving end, L1 is the self-inductance of the transmitting coil, and R... p The real part of the equivalent input impedance, C1 is the emitter parallel compensation capacitor, R1 is the primary-side emitter internal resistance, and X is the emitter resistance. p ω is the imaginary part of the equivalent input impedance, and ω is the inverter output angular frequency.

[0017] As a further improvement to this application, the calculation of the mutual inductance parameters between the transmitting coil and the receiving coil includes:

[0018] Calculate the real part of the complex impedance at the secondary receiving end based on the tangent of the complex impedance at the secondary receiving end.

[0019] Based on the real part of the complex impedance of the secondary receiving end and the real part of the equivalent input impedance, the mutual inductance parameters between the transmitting coil and the receiving coil are calculated in a decoupled manner.

[0020] As a further improvement to this application, the load characteristics include load power, load current, and load voltage; based on transmission efficiency and load parameters, the load characteristics of the wireless power transmission system are estimated as follows:

[0021] Calculate the primary-side transmitter power based on the output voltage and output current of the primary-side transmitter inverter;

[0022] Calculate load power based on primary-side transmit power and transmission efficiency;

[0023] Calculate the load current and load voltage based on the load power and load parameters.

[0024] As a further improvement to this application, the calculation of the load parameters of the secondary receiving end includes:

[0025] Based on the tangent of the complex impedance of the secondary receiving end, the load parameters of the secondary receiving end are calculated in combination with the first fitting parameters, as shown in the calculation formula (2).

[0026] R L =∑a n ·k n (2)

[0027] Among them, a n Here, is the first fitting parameter, k is the tangent of the complex impedance at the secondary receiving end, n is the polynomial order, and R0 is the final value. L For load parameters.

[0028] As a further improvement of this application, based on the real part of the complex impedance of the secondary receiving end and the real part of the equivalent input impedance, the mutual inductance parameters between the transmitting coil and the receiving coil are decoupled and calculated as shown in the calculation formula (3).

[0029]

[0030] Where ω is the inverter output angular frequency, M 12 R is the mutual inductance between the transmitting coil and the receiving coil. s R is the real part of the complex impedance at the secondary receiving end. p R1 is the real part of the equivalent input impedance, k is the tangent of the complex impedance at the secondary receiving end, and R1 is the internal resistance at the primary transmitting end.

[0031] As a further improvement to this application, estimating the transmission efficiency of a wireless power transfer system based on the tangent of the equivalent input impedance and the complex impedance of the secondary receiver includes:

[0032] Calculate the real part of the complex impedance at the secondary receiving end based on the tangent of the complex impedance at the secondary receiving end.

[0033] The transmission efficiency is calculated based on the real part of the equivalent input impedance and the real part of the complex impedance at the secondary receiving end, as shown in Equation (4).

[0034]

[0035] Among them, R s R is the real part of the complex impedance at the secondary receiving end. p R1 is the real part of the equivalent input impedance, R2 is the internal resistance of the primary side transmitter, and R2 is the internal resistance of the secondary side receiver.

[0036] As a further improvement of this application, the real part of the complex impedance of the secondary receiving end is calculated based on the tangent of the complex impedance of the secondary receiving end as shown in the calculation formula (5).

[0037] Rs=∑b n ·k n (5)

[0038] Among them, b n is the second fitting parameter, k is the tangent of the complex impedance at the secondary receiving end, n is the polynomial order, and Rs is the real part of the complex impedance at the secondary receiving end.

[0039] As a further improvement of this application, the load power is calculated based on the primary side transmit power and transmission efficiency as shown in the calculation formula (6);

[0040] P L =ηP P (6);

[0041] Among them, P L Where P is the load power, η is the transmission efficiency, and P is the transmission efficiency. P Primary-side transmit power

[0042] The load current is calculated based on the load power and load parameters as shown in equation (7);

[0043]

[0044] Among them, I L R is the load current. L For load parameters;

[0045] The load voltage is calculated based on the load power and load parameters as shown in formula (9);

[0046]

[0047] Among them, U L This is the load voltage.

[0048] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0049] 1. By collecting the output voltage and output current of the primary-side transmitter inverter, the voltage across the parallel compensation capacitor and the current in the transmitter coil are calculated, thereby obtaining the equivalent input impedance of the primary-side transmitter. Based on the equivalent input impedance, the tangent of the complex impedance of the secondary-side receiver is decoupled and calculated, and the load parameters of the secondary-side receiver and the mutual inductance parameters between the transmitter and receiver coils are calculated. This eliminates the need for complex mathematical modeling and a large amount of prior knowledge, reducing the dependence on accurate measurement of the system's internal structure and parameters, and solving the problems of complexity and reliance on prior knowledge in existing methods.

[0050] 2. By converting the equivalent input impedance into a complex form and, based on the real and imaginary parts of the equivalent input impedance, combined with the self-inductance of the transmitting coil, the internal resistance of the primary transmitting end, and the compensation capacitor, the tangent value of the complex impedance at the secondary receiving end is calculated in a decoupled manner. This achieves accurate calculation of the tangent value of the complex impedance at the secondary receiving end, thereby enabling precise calculation of the load parameters at the secondary receiving end and the mutual inductance parameters between the transmitting and receiving coils. Based on the equivalent input impedance and the tangent value of the complex impedance at the secondary receiving end, the transmission efficiency of the wireless power transmission system is estimated. Based on the transmission efficiency and load parameters, the load characteristics of the wireless power transmission system are estimated, improving the accuracy of parameter estimation and solving the problem of low accuracy in existing methods.

[0051] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0052] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0053] Figure 1 This is a schematic flowchart of a method for estimating parameters of a wireless power transmission system according to an embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of a wireless power transmission system provided in an embodiment of the present invention. Detailed Implementation

[0055] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0056] A specific embodiment of the present invention discloses a method for estimating parameters of a wireless power transmission system, such as... Figure 1 As shown, the wireless power transmission system includes a primary-side transmitter and a secondary-side receiver. The method for estimating the parameters of the wireless power transmission system includes the following steps:

[0057] S1. Collect the output voltage and output current of the primary-side transmitter inverter.

[0058] The output voltage and current of the primary-side transmitter inverter can be acquired by connecting high-precision voltage and current sensors to the inverter's output terminals. The voltage sensor monitors the voltage changes at the inverter's output terminals in real time, while the current sensor measures the current flowing through the inverter's output terminals.

[0059] In a wireless power transmission system, the primary-side transmitter inverter is used to convert direct current into high-frequency alternating current to provide energy to the transmitting coil, enabling it to transmit electrical energy outward in the form of a high-frequency magnetic field.

[0060] S2. Based on the output voltage and output current, calculate the voltage across the parallel compensation capacitor and the current in the transmitting coil.

[0061] The coils at the primary transmitting end and the secondary receiving end of a wireless power transmission system need to be connected to a compensation network. Bilateral LCC compensation ensures stable power transmission across the entire range of offset and load variations. For example... Figure 2 As shown, the wireless power transfer system comprises a high-frequency inverter, a transmitter compensation network, a transmitter coil, a receiver coil, a receiver compensation network, and a rectifier circuit. The transmitter compensation network includes a transmitter series compensation capacitor C1 and a transmitter parallel compensation capacitor C... f1 The parallel compensation capacitor C is used for transmitting. f1 Used to compensate for the output impedance of the inverter, improving the system's power factor and transmission efficiency. The current in the transmitting coil reflects the strength of the magnetic field generated by the transmitting coil. The receiver compensation network consists of the receiver inductor L. f2 Receive parallel compensation capacitor C f2 It consists of a series compensation capacitor C2.

[0062] Transmitter parallel compensation capacitor C f1 The voltages on both sides are shown in the calculation formula (1);

[0063]

[0064] in, Parallel compensation capacitor C for transmission f1 The voltage on both sides; This refers to the output voltage. ω is the output current; ω is the inverter output angular frequency; j is the imaginary unit.

[0065] The current in the transmitting coil is shown in calculation formula (2);

[0066]

[0067] in, L is the current in the transmitting coil. f1 For the primary-side emitter inductance, C f1Parallel compensation capacitor for the transmitter.

[0068] S3. Calculate the equivalent input impedance of the primary-side transmitter terminal based on the voltage of the transmitting parallel compensation capacitor and the current of the transmitting coil.

[0069] The equivalent input impedance of the primary-side transmitter is calculated by the voltage of the transmitter parallel compensation capacitor and the current of the transmitter coil. Specifically, the equivalent input impedance of the primary-side transmitter is calculated as shown in equation (3);

[0070]

[0071] Among them, Z p This is the equivalent input impedance of the primary-side emitter.

[0072] S4. Calculate the tangent of the complex impedance of the secondary receiving end based on the equivalent input impedance decoupling. Calculate the load parameters of the secondary receiving end and the mutual inductance parameters between the transmitting coil and the receiving coil based on the tangent of the complex impedance of the secondary receiving end.

[0073] The complex impedance of the secondary receiver reflects the overall resistance of the receiver to electrical energy. Its tangent value is the ratio of the imaginary part to the real part of the complex impedance of the secondary receiver, reflecting the phase characteristics of the receiver circuit. The load parameter refers to the load resistance of the secondary receiver, and the mutual inductance parameter refers to the degree of magnetic coupling between the primary transmitting coil and the secondary receiving coil.

[0074] Specifically, calculating the tangent of the complex impedance at the secondary receiving end based on the equivalent input impedance decoupling includes:

[0075] The equivalent input impedance is converted into a complex form. Based on the real and imaginary parts of the equivalent input impedance, combined with the self-inductance of the transmitting coil, the internal resistance of the primary transmitting end, and the compensation capacitor, the tangent value of the complex impedance of the secondary receiving end is decoupled and calculated as shown in formula (4).

[0076]

[0077] Where k is the tangent of the complex impedance at the secondary receiving end, L1 is the self-inductance of the transmitting coil, and R... p The real part of the equivalent input impedance, C1 is the emitter parallel compensation capacitor, R1 is the primary-side emitter internal resistance, and X is the emitter resistance. p ω is the imaginary part of the equivalent input impedance, and ω is the inverter output angular frequency.

[0078] The real part of the equivalent input impedance is shown in Equation (5);

[0079]

[0080] Among them, Z spLet be the reflected impedance from the secondary coil to the primary coil. The reflected impedance from the secondary coil to the primary coil is shown in calculation formula (6).

[0081]

[0082] Among them, R s X is the real part of the complex impedance at the secondary receiving end. s This is the imaginary part of the complex impedance at the secondary receiving end.

[0083] The calculation of the mutual inductance parameters between the transmitting and receiving coils includes:

[0084] Calculate the real part of the complex impedance at the secondary receiving end based on the tangent of the complex impedance at the secondary receiving end.

[0085] Based on the real part of the complex impedance of the secondary receiving end and the real part of the equivalent input impedance, the mutual inductance parameters between the transmitting coil and the receiving coil are calculated in a decoupled manner.

[0086] Based on the real part of the complex impedance of the secondary receiving end and the real part of the equivalent input impedance, the mutual inductance parameters between the transmitting coil and the receiving coil are decoupled and calculated as shown in Equation (7).

[0087]

[0088] Where ω is the inverter output angular frequency, M 12 R is the mutual inductance between the transmitting coil and the receiving coil. s R is the real part of the complex impedance at the secondary receiving end. p R1 is the real part of the equivalent input impedance, k is the tangent of the complex impedance at the secondary receiving end, and R1 is the internal resistance at the primary transmitting end.

[0089] The calculation of the load parameters at the secondary receiver includes:

[0090] Based on the tangent of the complex impedance of the secondary receiving end, the load parameters of the secondary receiving end are calculated in combination with the first fitting parameters, as shown in the calculation formula (8).

[0091] R L =Σa n ·k n (8)

[0092] Among them, a n Here, is the first fitting parameter, k is the tangent of the complex impedance at the secondary receiving end, n is the polynomial order, and R0 is the final value. L For load parameters.

[0093] S5. Estimate the transmission efficiency of the wireless power transmission system based on the tangent of the equivalent input impedance and the complex impedance at the secondary receiver. Based on the transmission efficiency and load parameters, estimate the load characteristics of the wireless power transmission system. Load characteristics include load power, load current, and load voltage. Load power refers to the actual electrical power consumed by the load at the secondary receiver, reflecting the load's utilization of electrical energy. Load current, the current flowing through the load, together with the load voltage, determines the load power. Load voltage refers to the voltage across the load, which can be used to evaluate the load's operating state and system performance.

[0094] Transmission efficiency refers to the ratio of the actual power received at the secondary side receiver to the power input at the primary side transmitter in a wireless power transmission system, reflecting the effectiveness of power transmission in the system.

[0095] Estimating the transmission efficiency of a wireless power transfer system based on the tangent of the equivalent input impedance and the complex impedance at the secondary receiver includes:

[0096] Based on the tangent of the complex impedance at the secondary receiving end, the real part of the complex impedance at the secondary receiving end is calculated; the calculation of the real part of the complex impedance at the secondary receiving end is shown in the calculation formula (9).

[0097] R s =∑b n ·k n (9)

[0098] Among them, b n is the second fitting parameter, k is the tangent of the complex impedance at the secondary receiving end, n is the polynomial order, and Rs is the real part of the complex impedance at the secondary receiving end.

[0099] The imaginary part of the complex impedance at the secondary receiving end is shown in the calculation formula (10);

[0100] X S =∑c n ·k n (10)

[0101] Among them, c n The third fitting parameter is denoted by , k is the tangent of the complex impedance at the secondary receiving end, n is the polynomial order, and Xs is the imaginary part of the complex impedance at the secondary receiving end. The first, second, and third fitting parameters are all predetermined experimentally.

[0102] The transmission efficiency is calculated based on the real part of the equivalent input impedance and the real part of the complex impedance at the secondary receiving end, as shown in Equation (11).

[0103]

[0104] Among them, R s R is the real part of the complex impedance at the secondary receiving end. pR1 is the real part of the equivalent input impedance, R2 is the internal resistance of the primary side transmitter, and R2 is the internal resistance of the secondary side receiver.

[0105] Based on transmission efficiency and load parameters, estimating the load characteristics of a wireless power transmission system includes:

[0106] Calculate the primary-side transmitter power based on the output voltage and output current of the primary-side transmitter inverter;

[0107] Calculate load power based on primary-side transmit power and transmission efficiency;

[0108] Calculate the load current and load voltage based on the load power and load parameters.

[0109] The load power is calculated based on the primary side transmit power and transmission efficiency as shown in equation (12);

[0110] P L =ηP P (12);

[0111] Among them, P L Where P is the load power, η is the transmission efficiency, and P is the transmission efficiency. P Primary-side transmit power

[0112] The load current is calculated based on the load power and load parameters as shown in formula (13);

[0113]

[0114] Among them, I L R is the load current. L For load parameters;

[0115] The load voltage is calculated based on the load power and load parameters as shown in formula (14);

[0116]

[0117] Among them, U L This is the load voltage.

[0118] The above embodiments of the present invention can achieve at least the following beneficial effects:

[0119] 1. By collecting the output voltage and output current of the primary-side transmitter inverter, the voltage across the transmitter parallel compensation capacitor and the current of the transmitter coil are calculated, thereby obtaining the equivalent input impedance of the primary-side transmitter. Based on the equivalent input impedance, the tangent of the complex impedance of the secondary-side receiver is decoupled and calculated, and the load parameters of the secondary-side receiver and the mutual inductance parameters between the transmitter coil and the receiver coil are calculated. This eliminates the need for complex mathematical modeling and a large amount of prior knowledge, reducing the dependence on the accurate measurement of the internal structure and parameters of the system, and solving the problems of complexity and reliance on prior knowledge in existing methods.

[0120] 2. By converting the equivalent input impedance into a complex form and, based on the real and imaginary parts of the equivalent input impedance, combined with the self-inductance of the transmitting coil, the internal resistance of the primary transmitting end, and the compensation capacitor, the tangent value of the complex impedance at the secondary receiving end is calculated in a decoupled manner. This achieves accurate calculation of the tangent value of the complex impedance at the secondary receiving end, thereby enabling precise calculation of the load parameters at the secondary receiving end and the mutual inductance parameters between the transmitting and receiving coils. Based on the equivalent input impedance and the tangent value of the complex impedance at the secondary receiving end, the transmission efficiency of the wireless power transmission system is estimated. Based on the transmission efficiency and load parameters, the load characteristics of the wireless power transmission system are estimated, improving the accuracy of parameter estimation and solving the problem of low accuracy in existing methods.

[0121] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0122] 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 changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for estimating parameters of a wireless power transmission system, the wireless power transmission system comprising a primary-side transmitter and a secondary-side receiver, characterized in that, Includes the following steps: S1. Collect the output voltage and output current of the primary-side transmitter inverter; S2. Based on the output voltage and output current, calculate the voltage across the parallel compensation capacitor and the current in the transmitting coil. S3. Calculate the equivalent input impedance of the primary-side transmitter based on the voltage of the parallel compensation capacitor and the current of the transmitter coil. S4. Calculate the tangent of the complex impedance of the secondary receiving end based on the equivalent input impedance decoupling. Calculate the load parameters of the secondary receiving end and the mutual inductance parameters between the transmitting coil and the receiving coil based on the tangent of the complex impedance of the secondary receiving end. S5. Estimate the transmission efficiency of the wireless power transmission system based on the tangent of the equivalent input impedance and the complex impedance of the secondary receiving end. Estimate the load characteristics of the wireless power transmission system based on the transmission efficiency and load parameters.

2. The method for estimating parameters of a wireless power transmission system according to claim 1, characterized in that, The calculation of the tangent of the complex impedance at the secondary receiving end based on the equivalent input impedance decoupling includes: The equivalent input impedance is converted into a complex number. Based on the real and imaginary parts of the equivalent input impedance, combined with the self-inductance of the transmitting coil, the internal resistance of the primary transmitting end, and the compensation capacitor, the tangent of the complex impedance of the secondary receiving end is decoupled and calculated.

3. The method according to claim 2, characterized in that, The equivalent input impedance is converted into a complex form. Based on the real and imaginary parts of the equivalent input impedance, combined with the self-inductance of the transmitting coil, the internal resistance of the primary transmitting end, and the compensation capacitor, the tangent value of the complex impedance of the secondary receiving end is decoupled and calculated as shown in formula (1). Where k is the tangent of the complex impedance at the secondary receiving end, L1 is the self-inductance of the transmitting coil, and R... p The real part of the equivalent input impedance, C1 is the emitter parallel compensation capacitor, R1 is the primary-side emitter internal resistance, and X is the emitter resistance. p ω is the imaginary part of the equivalent input impedance, and ω is the inverter output angular frequency.

4. The method for estimating parameters of a wireless power transmission system according to claim 2, characterized in that, The calculation of the mutual inductance parameters between the transmitting and receiving coils includes: Calculate the real part of the complex impedance at the secondary receiving end based on the tangent of the complex impedance at the secondary receiving end. Based on the real part of the complex impedance of the secondary receiving end and the real part of the equivalent input impedance, the mutual inductance parameters between the transmitting coil and the receiving coil are calculated in a decoupled manner.

5. The method for estimating parameters of a wireless power transmission system according to claim 1, characterized in that, Load characteristics include load power, load current, and load voltage; Based on transmission efficiency and load parameters, estimating the load characteristics of a wireless power transmission system includes: Calculate the primary-side transmitter power based on the output voltage and output current of the primary-side transmitter inverter; Calculate load power based on primary-side transmit power and transmission efficiency; Calculate the load current and load voltage based on the load power and load parameters.

6. The method according to claim 2, characterized in that, The calculation of the load parameters at the secondary receiver includes: Based on the tangent of the complex impedance of the secondary receiving end, the load parameters of the secondary receiving end are calculated in combination with the first fitting parameters, as shown in the calculation formula (2). R L =Σa n ·k n (2) Among them, a n Here, is the first fitting parameter, k is the tangent of the complex impedance at the secondary receiving end, n is the polynomial order, and R0 is the final value. L For load parameters.

7. The method according to claim 4, characterized in that, Based on the real part of the complex impedance of the secondary receiving end and the real part of the equivalent input impedance, the mutual inductance parameters between the transmitting coil and the receiving coil are calculated as shown in Equation (3). Where ω is the inverter output angular frequency, M 12 R is the mutual inductance between the transmitting coil and the receiving coil. s R is the real part of the complex impedance at the secondary receiving end. p R1 is the real part of the equivalent input impedance, k is the tangent of the complex impedance at the secondary receiving end, and R1 is the internal resistance at the primary transmitting end.

8. The method for estimating parameters of a wireless power transmission system according to claim 2, characterized in that, Estimating the transmission efficiency of a wireless power transfer system based on the tangent of the equivalent input impedance and the complex impedance at the secondary receiver includes: Calculate the real part of the complex impedance at the secondary receiving end based on the tangent of the complex impedance at the secondary receiving end. The transmission efficiency is calculated based on the real part of the equivalent input impedance and the real part of the complex impedance at the secondary receiving end, as shown in Equation (4). Among them, R s R is the real part of the complex impedance at the secondary receiving end. p R1 is the real part of the equivalent input impedance, R2 is the internal resistance of the primary side transmitter, and R2 is the internal resistance of the secondary side receiver.

9. The method according to claim 4 or 8, characterized in that, Based on the tangent of the complex impedance at the secondary receiving end, the real part of the complex impedance at the secondary receiving end is calculated as shown in Equation (5). Rs=Σb n ·k n (5) Among them, b n is the second fitting parameter, k is the tangent of the complex impedance at the secondary receiving end, n is the polynomial order, and Rs is the real part of the complex impedance at the secondary receiving end.

10. The method according to claim 5, characterized in that, The load power is calculated based on the primary side transmit power and transmission efficiency as shown in equation (6); P L =ηP P (6); Among them, P L Where P is the load power, η is the transmission efficiency, and P is the transmission efficiency. P Primary-side transmit power The load current is calculated based on the load power and load parameters as shown in formula (7); Among them, I L R is the load current. L For load parameters; The load voltage is calculated based on the load power and load parameters as shown in formula (9); Among them, U L This is the load voltage.

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