Wireless power transmission system based on variable capacitance regulation and anti-offset method thereof

Abstract

The invention relates to the technical field of wireless electric energy transmission, in particular to a wireless electric energy transmission system based on variable capacitance regulation and control and an anti-offset method thereof. A wireless electric energy transmission system based on variable capacitance regulation and control comprises three power supply conversion modules which are arranged in parallel, the three power supply conversion modules are connected with an X-shaped-circumferential composite transmitting coil, the X-shaped-circumferential composite transmitting coil is arranged opposite to a receiving coil, the receiving coil is connected with a rectification module, and the rectification module is connected with a power supply. The output end of each power supply conversion module is connected with the X-shaped-circumferential composite transmitting coil through a variable capacitance regulation and control assembly, the invention also discloses an anti-offset method based on the system, through regulation and control of the variable capacitance regulation and control assembly, the adaptive capacity between the coil and the compensation topology is improved, the change of mutual inductance generated by offset is compensated, and the anti-offset performance of the X-shaped-circumferential composite transmitting coil is improved. And stable output of the system is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless power transmission, and particularly relates to a wireless power transmission system based on variable capacitance regulation and an anti-offset method thereof. BACKGROUND

[0002] In recent years, wireless power transmission (WPT) technology has shown broad application prospects in the fields of electric vehicles, implantable medical devices and underwater equipment due to its non-contact, safety and convenience. However, in the actual application process, the relative positions of the transmitting coil and the receiving coil inevitably deviate, including changes in the horizontal and vertical gaps and mismatch in the rotation angle around the center. These deviations cause the coupling coefficient and mutual inductance parameters to deviate significantly from the rated value, thereby causing fluctuations in the output power, current and efficiency, weakening the stability and robustness of the system. How to achieve constant output and high-efficiency transmission under complex offset conditions has become a key problem for breaking through the application of WPT technology. SUMMARY

[0003] The present application aims to provide a wireless power transmission system based on variable capacitance regulation and an anti-offset method thereof, which solves the above technical problems, provides different adjustment schemes for mutual inductance changes under different working conditions, improves the adaptation ability between the coil and the compensation topology, compensates for the changes in mutual inductance caused by the offset, and ensures stable system output.

[0004] To achieve the above-mentioned purpose, the present application provides a wireless power transmission system based on variable capacitance regulation, which comprises three power conversion modules arranged side by side, the three power conversion modules are connected with an X-shaped-ring circumference composite transmitting coil, the X-shaped-ring circumference composite transmitting coil is oppositely arranged with a receiving coil, the receiving coil is connected with a rectifier module, and the output end of each power conversion module is connected with the X-shaped-ring circumference composite transmitting coil through a variable capacitance regulation component. The variable capacitance regulation component comprises a transmitting side compensation inductor, a compensation variable capacitor and a coil resonance variable capacitor, the transmitting side compensation inductor, the coil resonance variable capacitor and a transmitting coil in the X-shaped-ring circumference composite transmitting coil are connected in series, one end of the compensation variable capacitor is connected to a connecting line between the transmitting side compensation inductor and the coil resonance variable capacitor, and the other end of the compensation variable capacitor is connected to the output end of the transmitting coil.

[0005] Preferably, the X-shaped-ring circumference composite transmitting coil comprises an X-shaped transmitting coil, a first ring circumference transmitting coil and a second ring circumference transmitting coil are arranged on the circumference of the X-shaped transmitting coil, the first ring circumference transmitting coil and the second ring circumference transmitting coil are both provided with two and are symmetrically arranged, the first ring circumference transmitting coil and the second ring circumference transmitting coil are alternately arranged, the inner sides of the first ring circumference transmitting coil and the second ring circumference transmitting coil are parallel to the X-shaped transmitting coil, and the outer sides of the first ring circumference transmitting coil and the second ring circumference transmitting coil are arc-shaped.

[0006] Preferably, the receiving coil is a toroidal coil, and a receiving coil resonant capacitor and a receiving-side coil inductor are connected in series with the receiving coil. One end of the receiving-side compensation capacitor is connected to the connecting line between the receiving coil resonant capacitor and the receiving-side compensation inductor, and the other end of the receiving-side compensation capacitor is connected to the input terminal of the receiving coil.

[0007] The specific steps of the anti-migration method for a wireless power transfer system based on variable capacitor control described above are as follows: Step S1: Initialize the parameters of the compensation variable capacitor and the coil resonance variable capacitor; Step S2: Collect the output current of the rectifier module; Step S3: Determine whether the error rate of the output current exceeds the set range based on the output current collected in step S2 and the reference output current; When the error rate of the output current does not exceed the set range, the rectifier module directly outputs the output current; When the error rate of the output current exceeds the set range, the parameters of the compensation variable capacitor and the coil resonant variable capacitor are updated. The compensated output current is calculated based on the updated parameters of the compensation variable capacitor and the coil resonant variable capacitor. The error rate of the output current is determined by comparing the compensated output current with the reference output current. The process continues until the compensated output current is within the set range, and then the rectifier module outputs the updated output current.

[0008] Preferably, step S1 is as follows: Step S11: Set the capacitance and upper and lower limits of the compensation variable capacitor and the coil resonance variable capacitor; Step S12: Calculate the output current using the capacity and upper and lower bounds determined in step S11. If there is no solution for the output current, return to step S11. If there is a solution for the output current, the capacity and upper and lower bounds of the compensation variable capacitor and the coil resonance variable capacitor are the initial parameters. Output current The calculation formula is as follows: ; in, and All are the first The adjustment coefficient of each, the adjustment coefficient Follow-up adjustment coefficient The change is determined based on the capacitance of the corresponding capacitor. The imaginary unit, This refers to the operating frequency of the inverter. For the first The mutual inductance between the transmitting and receiving coils of each, For receiving-side compensation capacitors, This is the equivalent load resistance. For the first The input voltage of each transmitting coil, For the first One of the transmitter-side compensation inductors, among which .

[0009] Preferably, in step S3, the reference output current is used. The calculation formula is as follows: ; The formula for calculating the error rate of the output current is as follows: ; in, The error rate of the output current. This is the output current.

[0010] Preferably, a two-degree-of-freedom control system with a common channel and a balanced channel is adopted, and the control model expression is as follows: ; in, and The first Secondary common control quantity and balance control quantity and The first Secondary common control quantity and balance control quantity and These are the public passage proportion coefficient and the public passage integral coefficient, respectively. To balance channel gain, To control the cycle, and divided into Safety margin indicators of the channel and Safety margin indicators for the channel; pass and After the update Channels and The signal parameters of the channel are calculated using the following formula: ; in, and The updated versions are as follows: Channels and Channel signal parameters, To assign weights, For update functions; , and They are respectively The lower and upper bounds of the channel; , and They are respectively The lower and upper bounds of the channel.

[0011] Preferably, when the receiving coil rotates around itself and is offset horizontally and vertically, the expression for the output current is as follows: ; in, The output current under offset conditions. It is a fixed constant. and They are respectively Channels and Channel signal parameters, Channel signal parameter following The changes in channel signal parameters are calculated using the following formula: ; make , For the first Error rate of the output current collected each time For the first The output current of the second acquisition, of which and It is related to the capacitance of the corresponding capacitor. follow Synchronous changes; Through the updated Channels and The signal parameters of the channel are used to calculate the compensated output current. Iterate and update until the compensated output current is within the set range.

[0012] Therefore, the present invention adopts the above-mentioned wireless power transmission system based on variable capacitor control and its anti-offset method, which has the following advantages: no other topological components are required, the steady-state consistency is better compared with other translation / rotation cases, the variable capacitor is controlled according to the offset, and the mutual inductance drift is compensated by continuously tuning the equivalent capacitance to achieve constant current output under various operating conditions, and the overall output remains stable with small fluctuations.

[0013] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0014] Figure 1 This is a circuit topology diagram of a wireless power transfer system based on variable capacitor control according to the present invention; Figure 2This is a schematic diagram of the variable capacitor structure of the present invention; Figure 3 This is the operating waveform of the variable capacitor in this invention; Figure 4 This is an equivalent circuit diagram of a decoupling wireless power transfer system based on variable capacitor control according to the present invention. Figure 5 This is a flowchart of the anti-offset method of the present invention; Figure 6 The adjustment coefficient of this invention Correlation curves with variable capacitors; Figure 7 The adjustment coefficient of this invention Correlation curves with variable capacitors; Figure 8 This is a schematic diagram of the first type of working condition motion according to the present invention; Figure 9 This is a diagram showing the output current variation under the first type of operating condition of the present invention; Figure 10 This is the output transmission efficiency diagram for the first type of operating condition of the present invention; Figure 11 This is a schematic diagram of the horizontal movement under the second type of working condition of the present invention; Figure 12 This is a schematic diagram of the vertical movement under the second type of working condition of the present invention; Figure 13 This is a graph showing the change in output current during horizontal movement of the present invention; Figure 14 This is a diagram showing the output transmission efficiency of the present invention during horizontal movement; Figure 15 This is a graph showing the change in output current during vertical movement of the present invention; Figure 16 This is a diagram showing the output transmission efficiency of the present invention during vertical movement; Figure 17 This is a schematic diagram of the third type of working condition of the present invention, showing a 90° counterclockwise rotation. Figure 18 This is a schematic diagram of the third type of working condition of the present invention, showing a 120° counterclockwise rotation. Figure 19 This is a diagram showing the output current variation under the third type of operating condition of the present invention; Figure 20 This is the output transmission efficiency diagram for the third type of operating condition of the present invention.

[0015] Figure Labels 1. X-shaped transmitting coil; 2. First circumferential transmitting coil; 3. Second circumferential transmitting coil; 4. Receiving coil. Detailed Implementation

[0016] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0017] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0018] like Figure 1 As shown, a wireless power transmission system based on variable capacitor control includes three power conversion modules arranged in parallel, which are connected to an X-shaped-circular composite transmitting coil.

[0019] The X-shaped-circumferential composite transmitting coil includes an X-shaped transmitting coil 1, around which a first circumferential transmitting coil 2 and a second circumferential transmitting coil 3 are arranged. Two of each type of transmitting coil are symmetrically arranged, alternating between them. The inner sides of the first and second circumferential transmitting coils 2 and 3 are parallel to the X-shaped transmitting coil 1, while their outer sides are arc-shaped. The three sets of transmitting coils are symmetrically distributed at 120° angles in space. Due to symmetry, the magnetomotive force components generated by the three sets of transmitting coils in space satisfy the following formula: ; The net magnetic flux of any external disk coil connected to these three-phase windings is zero, and the mutual inductance of the coils is as follows: ; in, The mutual inductance between the X-shaped transmitting coil 1 and the first toroidal transmitting coil 2 The number of turns of the first circumferential transmitting coil 2. For current The net magnetic flux generated when it passes through the first circumferential transmitting coil 2, and the mutual inductance between the transmitting coils. , and The values ​​are approximately canceled out to 0 under symmetrical excitation conditions, and this ring magnetic coupling transmitting coil structure can generate a natural decoupling magnetic field.

[0020] The output of each power conversion module is connected to an X-shaped toroidal composite transmitting coil via a variable capacitor control component. The input of the power conversion module is a DC input voltage. Figure 1 In , as well as The primary-side full-bridge inverter converts it into AC voltage. Figure 1 In , as well as The operating frequency is 100kHz. The inductances of the three transmitting coils are respectively... , as well as The currents flowing through the three transmitting coils are respectively , as well as Three transmitting coils are coplanar, of equal size, with a fixed number of turns and uniformly distributed at 120°. No magnetic material is used; their mutual inductance is determined solely by their geometric orientation and satisfies superposition and reciprocity relations. To synthesize a fixed-amplitude, steerable magnetic field in space, the three excitation currents are as follows: ; in, The peak value of the sinusoidal current. For alternating current frequency, It is the frequency of current modulation. , as well as These are the mutual inductances between the three transmitting coils and the receiving coils.

[0021] The variable capacitance control component includes an emitter-side compensation inductor ( , as well as The current flowing through it is , as well as ), compensation variable capacitor ( , as well as ) and coil resonant variable capacitor ( , as well as The transmitting side compensation inductor, the coil resonant variable capacitor, and the transmitting coil in the X-shaped-circular composite transmitting coil are connected in series. One end of the compensation variable capacitor is connected to the connecting line between the transmitting side compensation inductor and the coil resonant variable capacitor, and the other end of the compensation variable capacitor is connected to the output terminal of the transmitting coil.

[0022] Both the compensation variable capacitor and the coil resonant variable capacitor are variable capacitors (SCC) based on the adjustment coefficient, such as... Figure 2 As shown, SCC consists of two MOSFETs. and Connected in series with the capacitor Parallel connection, in order to reduce and Voltage stress, capacitor Used as a voltage divider in series connection, the operating waveform is as follows Figure 3 As shown, SCC is composed of sinusoidal current. The excitation is expressed as follows: ; in, This refers to the operating frequency of the inverter.

[0023] Flow through capacitor The current time interval is Then the capacitor voltage at both ends as follows: ; in, and The current flows into the capacitor respectively The moment and the present moment, .

[0024] The above equation represents a periodic capacitor voltage signal. By using Fourier series expansion and retaining the fundamental term, its fundamental component can be obtained. as follows: ; To reduce voltage stress, a series capacitor is used. Then the overall equivalent capacitance The expression can be as follows: ; in, This is the delay time.

[0025] and The selection of the capacitance and the delay time will affect the overall equivalent capacitance. The range of values ​​for .

[0026] The X-shaped toroidal composite transmitting coil and receiving coil 4 are positioned opposite each other. The receiving coil 4 is a toroidal coil, and its inductance and current are respectively... and The receiving coil 4 is connected in series with a receiving coil resonant capacitor. ) and receiving-side compensation inductor ( ), receiving side compensation inductor ( The capacitor is a variable capacitor. One end of the receiving-side compensation capacitor is connected to the connection line between the resonant capacitor of the receiving coil and the receiving-side compensation inductor, and the other end of the receiving-side compensation capacitor is connected to the input terminal of the receiving coil 4.

[0027] The receiving coil 4 is connected to a rectifier module. This is the input voltage of the secondary-side diode bridge rectifier. For filtering capacitors, and These are the DC charging current and voltage, respectively.

[0028] like Figure 4 As shown, the transmitting-side compensation inductance, the transmitting coil inductance, the receiving coil 4 inductance, and the receiving-side compensation inductance are all assumed to be ideal inductors in the modeling process, and their parasitic resistance is not considered. The output voltage of the power conversion module is as follows: ; Where K represents A, B, and C, respectively, which are different transmitting coils.

[0029] The equivalent load resistance is as follows: ; The relationship between the root mean square value of the rectifier input current phasor and the output current IO is as follows: ; After performing KVL equation calculations, we obtain: ; In the formula, k and K can be A, B, and C; After the introduction of SCC, the system's transmitting side operates under detuned conditions, while the receiving side is in full resonance: ; in, and All are the first The adjustment coefficient of each, the adjustment coefficient Follow-up adjustment coefficient The change is determined based on the capacitance of the corresponding capacitor. The imaginary unit represents the resonant state on the transmitting side. and A value of 0 indicates that the transmitting circuit is in complete resonance; a value other than 0 indicates incomplete resonance. and None of them are equal to zero.

[0030] Output current as follows: ; ; System efficiency as follows: ; As can be seen from the above formula, the output current is independent of the load and is constant. ; Where c is a constant, ; Change and The overall system adapts to load changes while maintaining a constant output current. Assume the output reference current is as follows: ; Constant current output means that the output current remains constant within ±5% of the reference value. That is, fluctuations in current within the range of 1.9~2.1A are considered constant current output. ; in, This represents the output current under different operating conditions.

[0031] like Figure 5 As shown, the specific steps of the anti-migration method for a wireless power transfer system based on variable capacitor control are as follows: Step S1: Initialize the parameters of the compensation variable capacitor and the coil resonance variable capacitor. Step S1 is detailed below: Step S11: Set the capacitance and upper and lower limits of the compensation variable capacitor and the coil resonance variable capacitor; Step S12: Calculate the output current using the capacity and upper and lower bounds determined in step S11. If there is no solution for the output current, return to step S11. If there is a solution for the output current, the capacity and upper and lower bounds of the compensation variable capacitor and the coil resonance variable capacitor are the initial parameters. Output current The calculation formula is as follows: ; in, and All are the first The adjustment coefficient of each, the adjustment coefficient Follow-up adjustment coefficient The change is determined based on the capacitance of the corresponding capacitor. The imaginary unit, This refers to the operating frequency of the inverter. For the first The mutual inductance between the transmitting and receiving coils of each, For receiving-side compensation capacitors, This is the equivalent load resistance. For the first The input voltage of each transmitting coil, For the first One of the transmitter-side compensation inductors, among which .

[0032] Step S2: Collect the output current of the rectifier module.

[0033] Step S3: Determine whether the error rate of the output current exceeds the set range based on the output current acquired in step S2 and the reference output current. In step S3, the reference output current... The calculation formula is as follows: ; The formula for calculating the error rate of the output current is as follows: ; in, The error rate of the output current. This is the output current.

[0034] When the error rate of the output current does not exceed the set range, the rectifier module directly outputs the output current; When the error rate of the output current exceeds the set range, the parameters of the compensation variable capacitor and the coil resonant variable capacitor are updated. The compensated output current is calculated based on the updated parameters of the compensation variable capacitor and the coil resonant variable capacitor. The error rate of the output current is determined by comparing the compensated output current with the reference output current. The process continues until the compensated output current is within the set range, and then the rectifier module outputs the updated output current.

[0035] The control model employs a two-degree-of-freedom control approach, consisting of a common channel and a balanced channel. The expression for the control model is as follows: ; in, and The first Secondary common control quantity and balance control quantity and The first Secondary common control quantity and balance control quantity and These are the public passage proportion coefficient and the public passage integral coefficient, respectively. To balance channel gain, To control the cycle, and divided into Safety margin indicators of the channel and The safety margin index of a channel measures the degree of distance from the boundary. The calculation method in this embodiment has low computational cost, is robust to parameter uncertainties, and can be directly mapped to SCC implementation.

[0036] pass and After the update Channels and The signal parameters of the channel are calculated using the following formula: ; in, and The updated versions are as follows: Channels and Channel signal parameters, Channel signal parameter following Changes in channel signal parameters To assign weights, For update functions; , and They are respectively The lower and upper bounds of the channel; , and They are respectively The lower and upper bounds of the channel.

[0037] The expression for the output current is as follows, considering the rotation of the receiving coil 4 around itself and its horizontal and vertical offset: ; in, The output current under offset conditions. It is a fixed constant. and They are respectively Channels and The signal parameters of the channel are calculated using the following formula: ; make , For the first Error rate of the output current collected each time For the first The output current of the second acquisition, of which and It is related to the capacitance of the corresponding capacitor. follow Synchronous changes, such as Figures 6-7 As shown. The increase in the capacitance corresponds to... and The increase is monotonous, but the rate of increase is gradually slowing down.

[0038] Through the updated Channels and The signal parameters of the channel are used to calculate the compensated output current. Iterate and update until the compensated output current is within the set range. Adjust the coefficient. and By linearizing through monotonic transformation, and using only the current error as a basis, two equivalent control quantities are adjusted in a closed loop to make the output current converge to the desired value over the entire offset range. .

[0039] To evaluate the impact of pose perturbation on the output current, a pose vector is introduced under the premise of a three-emitter symmetrical array + air-core coil + unified excitation. ,in, This is a horizontal displacement; It is a vertical gap; The azimuth angle around the center of the array; γ is the tilt angle of the receiving coil; γ is the angle between the center of the receiving coil and the center of the transmitting coil.

[0040] The system model was built using Mworks, and different operating conditions were simulated using different ranges of mutual inductance variation. To verify the anti-migration degree of the proposed anti-migration method under three types of operating conditions, all simulations were carried out at the rated operating frequency and predetermined compensation parameters, and compared with the ±5% target band for evaluation.

[0041] First type of operating condition: Receiving coil 4 rotates around itself. For example... Figure 8 As shown.

[0042] Center alignment and fixed position, position parameters =0, =110mm, =0, γ=0. Define the spin angle as... Due to the symmetry of the transmitting coil structure, we only consider the case of rotation around the X-axis. The offset was scanned at different angles with a step size of 30°. The simulation results for output current and transmission efficiency are as follows: Figures 9-10 As shown. Each offset point is represented by a cylinder indicating different loads. The distribution is represented by upper / middle / lower envelopes, indicating extreme values ​​and median trends. Due to the symmetry of the structure, only the distribution is considered. Variations within the range of 0° to 90°. When As the temperature increases from 0° to 90°, under various loads... The overall current shows a slight downward trend, with a maximum of 2.03A and an error rate of 1.5%, and a minimum of 1.95A and an error rate of 2.5%. The overall distribution falls within a tolerance band of ±0.05A. This varies with the rotation angle. The efficiency increased from 0° to 90°. The median efficiency at each load decreased from 72% to 69%, while the upper / lower envelope remained within the range of 74% to 66%, which is relatively high overall.

[0043] Second type of operating condition: horizontal and vertical offset of receiving coil 4.

[0044] To evaluate the anti-offset capability in the horizontal and vertical directions, 1 / 4 of the characteristic dimension of receiving coil 4 was set as the main control range. Mutual inductance values ​​were simulated with vertical offsets of 0.5 cm and horizontal offsets of 0.25 cm each time. Figure 11 and Figure 12 As shown, due to the symmetry of the structure, the horizontal offsets X and Y are the same, so only the offset in X is considered. To evaluate the impact of positional mismatch on constant current performance, in Under the condition of z=40mm.

[0045] The horizontal offset was scanned, and the simulation results for output current and transmission efficiency are as follows: Figure 13 and Figure 14 As shown. When the offset increases from 10mm to 50mm, The median efficiency decreased from 2.01A to 1.96A. Across the entire load range, the maximum current was 2.025A with an error of 1.25%, and the minimum was 1.95A with an error of 2.5%. The overall distribution fell within a tolerance band of ±0.05A. As the offset increased from 10mm to 50mm, the median system efficiency exhibited an approximately monotonically decreasing trend (from approximately 89% to approximately 80%), with the upper and lower envelopes varying between approximately 90% and 81% and 86% and 75%, respectively, indicating that the efficiency dispersion under different loads increased with increasing offset.

[0046] During the vertical offset process, the height of the receiving coil is changed. z Vertical scanning settings =10mm, for each offset point, record the steady-state output current. To evaluate the proposed scheme's resistance to displacement and upper limit of error under positional offset, simulation results for output current and transmission efficiency are as follows: Figure 15 and Figure 16 As shown, as z increases from 20mm to 60mm, the output current... The median value was slightly higher than the reference value. =2.00A gradually decreases to 1.96A. The maximum output current is 2.05A, with an error of 2.5%; the minimum is 1.96A, with an error of 2%. In the vertical gap zUnder scanning conditions, the efficiency shows a trend of first increasing and then decreasing. When the air gap increases from 20mm to about 40mm, the median efficiency increases from 82.5% to 88% and reaches a peak. After further increasing to 60mm, the median value drops back to 81%. The corresponding upper and lower envelopes are between 91.5% and 78%, respectively, and expand symmetrically as the gap moves away from the optimum.

[0047] The third type of operating condition: the receiving coil 4 revolves around the transmitting coil, such as... Figure 17 and Figure 18 As shown.

[0048] To evaluate the rotational resistance to offset, in 45° z With a radius of 65mm, receiving coil 4 always faces the transmitting coil. Azimuth angle around the array center. The simulation results for the constantly changing output current and transmission efficiency are as follows: Figure 19 and Figure 20 As shown, due to its symmetry, only [the following is considered] The knot changes within the range of 0°–180°. (From...) Figure 19 It can be seen that when As the temperature increases from 0° to 90°, under various loads... The overall trend is slightly downward, with the median value decreasing from 2.02A to 1.98A; when When the current increases from 90° to 180°, the overall current rises slightly, with the median value increasing from 1.98A to 2.03A. The maximum current during the entire process is 2.05A with an error rate of 2.5%, and the minimum current is 1.965A with an error rate of 1.75%. The current distribution is within a tolerance band of ±0.05A. The system efficiency increased from 0° to 180°. The median efficiency remained between 81% and 79% under various loads; the upper / lower envelope remained between 84% and 75%, and the overall system efficiency remained stable above 75%.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A wireless power transmission system based on variable capacitor control, comprising three power conversion modules arranged in parallel, the three power conversion modules being connected to an X-shaped-toroidal composite transmitting coil, the X-shaped-toroidal composite transmitting coil being arranged opposite to a receiving coil, and the receiving coil being connected to a rectifier module, characterized in that: The output of each power conversion module is connected to an X-shaped-circular composite transmitting coil via a variable capacitor control component; The variable capacitor control component includes a transmitter-side compensation inductor, a compensation variable capacitor, and a coil resonant variable capacitor. The transmitter-side compensation inductor, the coil resonant variable capacitor, and the transmitter coil in the X-shaped-toroidal composite transmitter coil are connected in series. One end of the compensation variable capacitor is connected to the connection line between the transmitter-side compensation inductor and the coil resonant variable capacitor, and the other end of the compensation variable capacitor is connected to the output terminal of the transmitter coil.

2. The wireless power transfer system based on variable capacitor control according to claim 1, characterized in that: The X-shaped circumferential composite transmitting coil includes an X-shaped transmitting coil, with a first circumferential transmitting coil and a second circumferential transmitting coil arranged around the circumference of the X-shaped transmitting coil. There are two of each type of transmitting coil, arranged symmetrically. The first and second circumferential transmitting coils are arranged alternately. The inner sides of the first and second circumferential transmitting coils are arranged parallel to the X-shaped transmitting coil, and the outer sides of the first and second circumferential transmitting coils are arranged in an arc shape.

3. The wireless power transmission system based on variable capacitor control according to claim 2, characterized in that: The receiving coil is a toroidal coil. The receiving coil is connected in series with a receiving coil resonant capacitor and a receiving-side coil inductor. One end of the receiving-side compensation capacitor is connected to the connecting line between the receiving coil resonant capacitor and the receiving-side compensation inductor, and the other end of the receiving-side compensation capacitor is connected to the input terminal of the receiving coil.

4. A method for resisting drift in a wireless power transfer system based on variable capacitor control, as described in claim 3, characterized in that: The specific steps are as follows: Step S1: Initialize the parameters of the compensation variable capacitor and the coil resonance variable capacitor; Step S2: Collect the output current of the rectifier module; Step S3: Determine whether the error rate of the output current exceeds the set range based on the output current collected in step S2 and the reference output current; When the error rate of the output current does not exceed the set range, the rectifier module directly outputs the output current; When the error rate of the output current exceeds the set range, the parameters of the compensation variable capacitor and the coil resonant variable capacitor are updated. The compensated output current is calculated based on the updated parameters of the compensation variable capacitor and the coil resonant variable capacitor. The error rate of the output current is determined by comparing the compensated output current with the reference output current. The process continues until the compensated output current is within the set range, and then the rectifier module outputs the updated output current.

5. The anti-migration method for a wireless power transfer system based on variable capacitor control according to claim 4, characterized in that, Step S1 is as follows: Step S11: Set the capacitance and upper and lower limits of the compensation variable capacitor and the coil resonance variable capacitor; Step S12: Calculate the output current using the capacity and upper and lower bounds determined in step S11. If there is no solution for the output current, return to step S11. If there is a solution for the output current, the capacity and upper and lower bounds of the compensation variable capacitor and the coil resonance variable capacitor are the initial parameters. Output current The calculation formula is as follows: ； in, and All are the first The adjustment coefficient of each, the adjustment coefficient Follow-up adjustment coefficient The change is determined based on the capacitance of the corresponding capacitor. The imaginary unit, This refers to the operating frequency of the inverter. For the first The mutual inductance between the transmitting and receiving coils of each, For receiving-side compensation capacitors, This is the equivalent load resistance. For the first The input voltage of each transmitting coil, For the first One of the transmitter-side compensation inductors, among which .

6. The anti-migration method for a wireless power transfer system based on variable capacitor control according to claim 5, characterized in that, In step S3, the reference output current is used. The calculation formula is as follows: ； The formula for calculating the error rate of the output current is as follows: ； in, The error rate of the output current. This is the output current.

7. The anti-migration method for a wireless power transfer system based on variable capacitor control according to claim 6, characterized in that: The control model employs a two-degree-of-freedom control approach, consisting of a common channel and a balanced channel. The expression for the control model is as follows: ； in, and The first Secondary common control quantity and balance control quantity and The first Secondary common control quantity and balance control quantity and These are the public passage proportion coefficient and the public passage integral coefficient, respectively. To balance channel gain, To control the cycle, and divided into Safety margin indicators of the channel and Safety margin indicators for the channel; pass and After the update Channels and The signal parameters of the channel are calculated using the following formula: ； in, and The updated versions are as follows: Channels and Channel signal parameters, To assign weights, For update functions; , and They are respectively The lower and upper bounds of the channel; , and They are respectively The lower and upper bounds of the passage.

8. The anti-migration method for a wireless power transfer system based on variable capacitor control according to claim 7, characterized in that: The expression for the output current is as follows, considering the receiving coil's rotation around itself and its horizontal and vertical offset: ； in, The output current under offset conditions. It is a fixed constant. and They are respectively Channels and Channel signal parameters, Channel signal parameter following The changes in channel signal parameters are calculated using the following formula: ； make , For the first Error rate of the output current collected each time For the first The output current of the second acquisition, of which and It is related to the capacitance of the corresponding capacitor. follow Synchronous changes; Through the updated Channels and The signal parameters of the channel are used to calculate the compensated output current. Iterate and update until the compensated output current is within the set range.

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