Fibonacci double helix coupling mechanism and wireless power transmission system based on it

Abstract

The present invention relates to the field of wireless power transmission technology, and specifically discloses a Fibonacci double-helix coupling mechanism and a wireless power transmission system based thereon. The two transmitting coils of the transmitting mechanism are orthogonally distributed, and the two receiving coils of the receiving mechanism are orthogonally distributed. Each coil is arranged based on the Fibonacci interval into a flat solenoid coil with a sparse center and dense sides. When a horizontal or vertical offset or rotational offset occurs, the coupling coefficient is only moderately reduced, and the system has strong resistance to horizontal offset, vertical offset, and rotation. Moreover, the coupling mechanism still has strong resistance to horizontal offset and vertical offset after rotation, and the system has strong comprehensive anti-offset capability. The system uses a dedicated single-tube high-frequency resonant inverter with only one MOS tube, and the total harmonic distortion of the system current is very small. The constructed experimental prototype achieves a constant voltage 24V output within the range of ±70mm for vertical and horizontal offsets, and the overall system efficiency is not less than 92%.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, and in particular to a Fibonacci double-helix coupling mechanism and a wireless power transmission system based on the Fibonacci double-helix coupling mechanism. Background Art

[0002] Wireless power transfer (WPT) technology eliminates the need for physical contact and instead transmits energy through magnetic or electric field coupling. Compared to wired transmission, wireless power transfer offers greater security, flexibility, and reliability, and is widely used in powering electric vehicles, underwater exploration, aerospace, and implantable medical devices.

[0003] Furthermore, in most wireless charging scenarios, offset between the primary and secondary coils is unavoidable. As the offset distance increases, the coupling coefficient between the coils decreases dramatically, leading to a sharp drop in the output power, voltage, and efficiency of the WPT system. To ensure the stability of the output efficiency and voltage of WPT systems, researchers have conducted research in three areas: system control, compensation topology design, and magnetic coupling mechanism optimization. For example, adding an additional DC-DC converter to the WPT system or implementing phase shifting or frequency conversion control on the inverter to adjust the amplitude and phase of the voltage and current can avoid complex system control issues, but it also places specific requirements on system parameters. The coupling mechanism is a key component of the WPT system. Different coupling mechanisms will result in different changes in the coupling coefficient when subjected to horizontal offset or rotation. For example, circular coils have strong rotational resistance but weak horizontal offset resistance; DDQ coils and flat solenoid coils have strong offset resistance in a certain direction. While the equally spaced flat solenoid coil proposed by Harbin Institute of Technology significantly improves the coil's tolerance to lateral offset, it suffers from poor longitudinal and rotational offset resistance. Summary of the Invention

[0004] The present invention provides a wireless power transmission system based on a Fibonacci double-helix coupling mechanism, and solves the technical problem of how to design a magnetic coupling mechanism with strong comprehensive anti-deviation capability in the horizontal, vertical and rotational directions, and how to apply the magnetic coupling mechanism to the wireless power transmission system.

[0005] In order to solve the above technical problems, the present invention provides a Fibonacci double spiral coupling mechanism, including a transmitting mechanism and a receiving mechanism. The key point is that the transmitting mechanism includes a first transmitting coil L P1 and the second transmitting coil L P2 The receiving mechanism includes a first receiving coil L r1 and the second receiving coil L r2 ;

[0006] The first transmitting coil L P1 The winding method is: along the first direction, spirally winding based on the Fibonacci sequence interval from dense to sparse and then dense to form a flat block structure;

[0007] The second transmitting coil L P2 The winding method is as follows: along a second direction orthogonal to the first direction, spirally winding the first transmitting coil L in a dense, sparse, and then dense manner based on the Fibonacci sequence interval. P1 superior;

[0008] The first receiving coil L r1 The winding method is: spirally winding along the first direction based on the Fibonacci sequence interval first dense, then sparse, and then dense to form a flat block structure;

[0009] The second receiving coil L r2 The winding method is: along the second direction, based on the Fibonacci sequence interval, the first receiving coil L is spirally wound densely, then sparsely, and then densely. r1 superior.

[0010] Preferably, the transmitting mechanism further includes a first flat block magnetic core, the first transmitting coil L P1 wound on the first flat block magnetic core;

[0011] The receiving mechanism further includes a second flat block magnetic core, the first receiving coil L r1 Wound on the second flat block magnetic core.

[0012] The present invention also provides a wireless power transmission system based on the Fibonacci double helix coupling mechanism, the key of which is that the magnetic coupling mechanism of the system adopts the Fibonacci double helix coupling mechanism.

[0013] Preferably, the system includes a transmitting end; the transmitting end includes a DC power supply V dc , a first high-frequency inverter and a second high-frequency inverter connected in parallel to the DC power supply, and further comprising the first transmitting coil L connected to the first high-frequency inverter P1 and the second transmitting coil L connected to the second high frequency inverter P2 ;

[0014] The first high-frequency inverter and the second high-frequency inverter both adopt a single-transistor high-frequency resonant inverter, and the single-transistor high-frequency resonant inverter includes an inductor L f , capacitor C f , NMOS tube Q, capacitor C P , the inductor L f , NMOS tube Q, capacitor C PSequentially connected in series with the DC power supply V dc The source of the NMOS tube Q is connected to the inductor L between the positive and negative terminals. f , the drain is connected to the capacitor C P The gate is used as a control terminal for connecting to the first PWM signal generator, and the capacitor C f The first transmitting coil L is connected in parallel between the source and drain of the NMOS tube Q. P1 or the second transmitting coil L P2 In parallel with the capacitor C P At both ends of the DC power supply V dc The negative terminal of the

[0015] Preferably, the position of the NMOS tube Q is aligned with the capacitor C p The positions of the first transmitting coil L are swapped, and the first transmitting coil L P1 or the second transmitting coil L P2 The position of the capacitor C f Swap the positions.

[0016] Preferably, the inductor L f With the capacitor C f The input resonant angular frequency is between f satisfy:

[0017]

[0018] ∈[1.3,1.5] is the adjustment coefficient, and ω0 is the switching angular frequency of the NMOS tube Q.

[0019] Preferably, the system includes a receiving end; the receiving end includes the first receiving coil L r1 , the second receiving coil L r2 , further comprising connecting the first receiving coil L in series r1 Capacitor C r1 , connect the second receiving coil L in series r2 Capacitor C r2 , and connect the capacitor C r1 The first rectifier filter circuit is connected to the capacitor C r2 The second rectifier and filter circuit is connected in parallel with the filter capacitor C of the first rectifier and filter circuit connected in series. L1 and the filter capacitor C of the second rectifier filter circuit L2 load circuit.

[0020] Preferably, the resonant angular frequency ω of the system n It is equal to the switching angular frequency ω0 of the NMOS tube Q.

[0021] Preferably, the load circuit includes an NMOS tube Q3, a diode D5, an inductor L0, a capacitor C0, a load resistor R L , resistor R1, resistor R2, calculation module and drive circuit, filter capacitor C in series L1 and filter capacitor C L2 As a whole, it is regarded as a filter capacitor C L The drain of the NMOS tube Q3 is connected to the filter capacitor C L The source of the NMOS tube Q3 is connected to the negative terminal of the diode D5, and the positive terminal of the diode D5 is connected to the filter capacitor C L The other end of the inductor L0 and the capacitor C0 are connected in series and then connected to the two ends of the diode D5, and the load resistor R L connected to both ends of the capacitor C0, the resistor R1 and the resistor R2 are connected in series and then connected to both ends of the capacitor C0, the calculation module is used to collect the voltage of the resistor R1 or the resistor R2 and calculate the PWM signal based on the voltage to act on the drive circuit, and the drive circuit outputs the corresponding control signal to the gate of the NMOS tube Q3.

[0022] Preferably, the calculation module includes an ADC module, a filter, a PID controller, and a second PWM signal generator. The ADC module is used to collect the voltage of the resistor R1 or the resistor R2. The filter is used to perform median filtering using a bubble sort method to obtain a median voltage. The PID controller is used to obtain a calculated value through PID operation based on the median voltage and a reference voltage. The second PWM signal generator is used to generate a corresponding PWM signal from the calculated value and send it to the drive circuit.

[0023] The Fibonacci double-helix coupling mechanism provided by the present invention has two transmitting coils of a transmitting mechanism and two receiving coils of a receiving mechanism arranged orthogonally. Each coil is arranged based on Fibonacci spacing to form a flat solenoid coil with a sparse center and dense edges. When horizontal or vertical offset or rotational offset occurs, the coupling coefficient only decreases moderately, and the mechanism has strong resistance to horizontal offset, vertical offset, and rotation. Moreover, the coupling mechanism still has strong resistance to horizontal and vertical offset after rotation, and the mechanism as a whole has strong comprehensive anti-offset capability.

[0024] The wireless power transmission system based on the Fibonacci double-helix coupling mechanism provided by the embodiment of the present invention has a coupling mechanism using the Fibonacci double-helix coupling mechanism, which has a high comprehensive anti-offset capability. The two high-frequency inverters use a dedicated single-tube high-frequency resonant inverter. The inverter has the characteristics of simple circuit structure, simple driving circuit, only one NMOS tube, and the resonant state is independent of the load. It can effectively realize the zero-voltage turn-on of the main switch within a wide load resistance range from rated load to short circuit. The system output voltage is approximately a sine wave, and the total harmonic distortion of the system current is very small. The receiving end uses a closed-loop Buck converter after the rectifier to ensure that the system achieves constant voltage output. This example also shifts the excitation current of the two transmitting coils by 180° to suppress the ripple of the input current and reduce the current stress of the DC power supply. The constructed experimental prototype realizes that when V Buck When the voltage is between 26V and 48V and the air gap is 70mm, the constant voltage of 24V output is always maintained within the range of ±70mm in the vertical and horizontal deviation, and the overall system efficiency is not less than 92%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a three-dimensional diagram of the Fibonacci double helix coupling mechanism provided in Example 1 of the present invention;

[0026] Figure 2 : is the XZ plane magnetic field distribution diagram of the Fibonacci double helix coupling mechanism provided in Example 1 of the present invention; wherein:

[0027] Figure 2 (a) is the XZ plane magnetic field distribution diagram when the Fibonacci double helix coupling mechanism is positively aligned;

[0028] Figure 2 (b) is the XZ plane magnetic field distribution diagram when the Fibonacci double helix coupling mechanism is offset 300 mm toward the X axis;

[0029] Figure 3 : This is the XZ plane magnetic field distribution diagram of the equally spaced double-helix magnetic coupling mechanism provided in Example 1 of the present invention; wherein:

[0030] Figure 3 (a) is the XZ plane magnetic field distribution diagram when the double-helix magnetic coupling mechanism is aligned with equal spacing;

[0031] Figure 3 (b) is the XZ plane magnetic field distribution diagram when the double-helix magnetic coupling mechanism is arranged with equal spacing and offset 300 mm from the X axis;

[0032] Figure 4 : is a magnetic field distribution diagram in the XZ plane after the receiving coil of the Fibonacci double helix coupling mechanism provided in Example 1 of the present invention is rotated 45° about the Z axis; wherein:

[0033] Figure 4(a) is the magnetic field distribution diagram in the XZ plane after the receiving coil of the Fibonacci double helix coupling mechanism is rotated 45° about the Z axis;

[0034] Figure 4 (b) is the XZ plane magnetic field distribution diagram of the receiving coil of the Fibonacci double helix coupling mechanism after it is rotated 45° about the Z axis and offset 300 mm in the X direction;

[0035] Figure 5 This is a diagram of the XZ plane magnetic field distribution after the receiving coil of the equally spaced double-helix magnetic coupling mechanism provided in Example 1 of the present invention is rotated 45° along the Z axis; wherein:

[0036] Figure 5 (a) is the XZ plane magnetic field distribution diagram of the receiving coil of the double-helix magnetic coupling mechanism with equal spacing after being rotated 45° along the Z axis;

[0037] Figure 5 (b) is the XZ plane magnetic field distribution diagram of the receiving coil of the double-helix magnetic coupling mechanism with equal spacing, rotated 45° along the Z axis and offset 300 mm in the X direction;

[0038] Figure 6 1 is a comparison diagram of the variation trends of the offset coupling coefficients k1 and k4 along the X-axis provided in Example 1 of the present invention;

[0039] Figure 7 1 is a comparison diagram of the variation trends of the offset coupling coefficients k1 and k3 along the X-axis provided in Example 1 of the present invention;

[0040] Figure 8 1 is a comparison diagram of the variation trends of the offset coupling coefficients k4 and k5 along the X-axis provided in Example 1 of the present invention;

[0041] Figure 9 : This is a magnetic field vector diagram of the receiving coil of the Fibonacci double helix coupling mechanism provided in Example 1 of the present invention rotated 45 degrees;

[0042] Figure 10 is a circuit topology diagram of a wireless power transmission system based on a Fibonacci double helix coupling mechanism provided in Example 2 of the present invention;

[0043] Figure 11 is a calculation flow chart of the calculation module provided in Example 2 of the present invention;

[0044] Figure 12 The embodiment 2 of the present invention provides Figure 10 Equivalent circuit diagram of

[0045] Figure 13 1 is a soft switching waveform diagram of the NMOS transistor Q provided in Example 2 of the present invention;

[0046] Figure 14This is a comparison diagram of the harmonic content of the system input current provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0047] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings. The embodiments are provided for illustrative purposes only and are not to be construed as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of protection of the present invention. Many changes may be made to the present invention without departing from the spirit and scope of the present invention.

[0048] Example 1

[0049] How to achieve a strong comprehensive anti-deviation capability in the horizontal direction, vertical direction and rotation? The embodiment of the present invention provides a Fibonacci double helix coupling mechanism, such as Figure 1 As shown, the Fibonacci double spiral coupling mechanism includes a transmitting mechanism and a receiving mechanism, and the transmitting mechanism includes a first transmitting coil L P1 (ie transmitting coil 1) and the second transmitting coil L P2 (ie, the transmitting coil 2), the receiving mechanism includes a first receiving coil L r1 (ie receiving coil 1) and the second receiving coil L r2 (ie, receiving coil 2). The first transmitting coil L P1 The winding method is: along the first direction ( Figure 1 The X-axis direction is in the middle), and the flat block structure is formed by spiral winding based on the Fibonacci sequence interval, which is first dense, then sparse, and then dense. In order to enhance the magnetic coupling capability, the transmitting mechanism is also provided with a first flat block magnetic core (ie, magnetic core 1), the first transmitting coil L P1 Wound on the first flat block core.

[0050] The second transmitting coil L P2 The winding method is: along the second direction orthogonal to the first direction ( Figure 1 The Y-axis direction is in the middle), and the first transmitting coil L is spirally wound based on the Fibonacci sequence interval, first dense, then sparse, and then dense. P1 superior.

[0051] The first receiving coil L r1 The winding method is: along the first direction based on the Fibonacci sequence interval, the spiral winding is first dense, then sparse, and then dense to form a flat block structure. In order to enhance the magnetic coupling ability, the receiving mechanism is also provided with a second flat block magnetic core (i.e., magnetic core 2). The first receiving coil L r1 Wound on the second flat block core. The second receiving coil L r2 The winding method is as follows: along the second direction, spirally winding the first receiving coil L in a dense, sparse, and dense manner based on the Fibonacci sequence interval. r1 superior.

[0052] In this embodiment, "spiral winding based on the Fibonacci sequence, first dense, then sparse, then dense again" means that the spacing between the coils follows the Fibonacci sequence (0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144...), showing a density first and then sparseness. This density-first, then sparseness spacing is nearly symmetrical, resulting in a sparse center and dense sides, that is, first dense, then sparse, then dense again. This coil winding method ensures that the coupling coefficient of the coupling mechanism changes slowly when longitudinal and lateral offsets occur. Furthermore, the coils are orthogonally distributed, with coil 1 coupling only with coil 3 and coil 2 coupling only with coil 4. There is no other cross-coupling, reducing system complexity.

[0053] The primary reason why flat solenoid coils based on the Fibonacci sequence have such strong lateral and longitudinal resistance is that when the coupling mechanism deflects, only the magnetic resistance decreases, without generating opposing magnetic flux that would accelerate the reduction of the coupling coefficient. When the flat solenoid coils based on the Fibonacci sequence deflect horizontally or vertically, the magnetic field converges in opposite directions, slowing the reduction in magnetic resistance and thus enhancing the lateral resistance of the flat solenoid coils based on the Fibonacci sequence. Furthermore, when the receiving coil rotates, the magnetic fields emitted by the transmitting coils are orthogonal, so they are superimposed in the X and Y directions, forming a new magnetic field, further enhancing the rotation resistance of the flat solenoid coils based on the Fibonacci sequence.

[0054] To illustrate the anti-offset effect of the magnetic coupling mechanism based on the Fibonacci sequence arrangement provided in this example, a comparison is made between the magnetic coupling mechanism based on the Fibonacci sequence arrangement and the magnetic coupling mechanism based on the equal-interval arrangement. Except for the arrangement interval, the other parameters of the two mechanisms remain the same.

[0055] Since the receiving coil and transmitting coil in the YZ plane have the same distribution pattern as the receiving coil and transmitting coil in the XZ plane, and the coils in the two planes are orthogonal and there is no cross-coupling, the magnetic fields in the two planes have the same distribution pattern. Therefore, here we only need to compare the magnetic field distribution of the two different mechanisms in the XZ direction, which also represents the magnetic field distribution of the two different mechanisms in the YZ direction.

[0056] Figure 2 and Figure 3 The magnetic field distribution diagrams of two regions in the XZ plane are respectively shown for two different coupling mechanisms when the coupling mechanism is aligned and the receiving end is offset 300mm in the X direction. Figure 2 (a) and Figure 3 (a) shows that when the coupling mechanism is aligned, its magnetic field distribution is symmetrical, indicating that the magnetic flux passing through the coil is symmetrical, and the closer to the edge, the stronger the magnetic field. Figure 2 (b) and Figure 3(b) shows the magnetic field distribution of the receiving end of two different coupling mechanisms when the receiving end is offset by 300mm to the X axis. It can be concluded that the magnetic field on the left is basically concentrated on the receiving end, and a small part of the magnetic field on the right is also concentrated on the receiving end. The magnetic field weakens from left to right, indicating that the magnetic flux is concentrated to the left at this time. This means that when the receiving end is horizontally offset on the X axis and Y axis, the magnetic field of the coupling mechanism is concentrated in the opposite direction of its offset, thereby alleviating the increase of magnetic resistance. Secondly, by comparing Figure 2 and Figure 3 The number of coil grid turns in the center of the equally spaced mechanism is greater than that of the Fibonacci mechanism. However, due to the distance limit between the receiving and transmitting ends of the electric vehicle, the utilization rate is not very high. On the other hand, after an offset of 300mm, the equally spaced grid basically has no magnetic field distribution. However, due to its special distribution law, the magnetic field intensity at the edge of the Fibonacci grid is very high, so the receiving end can receive a large amount of magnetic field.

[0057] Figure 4 and Figure 5 The magnetic field distribution diagrams of two regions in the XZ plane for two different coupling mechanisms in positive alignment and after the receiving end rotates 45° along the Z axis. Figure 4 (a) and Figure 5 (a) shows that when the receiving end rotates 45°, since the two coils at the transmitting end are orthogonal, there will be two components in the horizontal and vertical directions on the receiving coil. After superposition, a stronger magnetic field distribution will appear in the figure, indicating that both have anti-rotation capabilities. Figure 4 (b) and Figure 5 As shown in Figure 2 (b), in the left half of the receiving coil, the Fibonacci grid has a stronger magnetic field than the equally spaced grid, indicating that the Fibonacci grid has better anti-deviation performance after rotation.

[0058] In summary, the orthogonal magnetic coupling mechanism of the double flat spiral coils arranged based on the Fibonacci sequence has stronger resistance to horizontal and rotational deviation than the orthogonal magnetic coupling mechanism of the double flat spiral coils arranged with equal spacing.

[0059] When the system is operating normally, it can be disassembled into two spiral coil coupling mechanisms with parallel inputs and series outputs. To further illustrate the anti-deviation characteristics of the orthogonal magnetic coupling mechanism based on the Fibonacci sequence arrangement of dual flat spiral coils, a simulation model was established using ANSYS MAXWELL. The simulation revealed how the mutual inductance and coupling coefficient of the magnetic coupling structure change under coil deflection.

[0060] Because receiving coils 1 and 2 have the same distribution pattern and the coils in the two planes are orthogonal, there is no cross-coupling. The same is true for transmitting coils 1 and 2. Therefore, here we only need to compare the relationship between transmitting coils 1 and receiving coils 1 of two different structures, which also represents the relationship between transmitting coils 2 and receiving coils 2 of two different structures.

[0061] The coupling coefficient between coils is an important indicator for measuring the anti-offset capability of a coupling mechanism. The coupling coefficient between the transmitting coil 1 and the receiving coil 1 of the orthogonal magnetic coupling mechanism of the double flat spiral coils arranged based on the Fibonacci sequence proposed in the present invention is defined as k1, and the coupling coefficient between the transmitting coil 2 and the receiving coil 2 is defined as k2; the coupling coefficient between the transmitting coil 1 and the receiving coil 1 of the orthogonal magnetic coupling mechanism of the double flat spiral coils arranged based on the Fibonacci sequence proposed in the present invention is defined as k3; the coupling coefficient between the transmitting coil 1 and the receiving coil 1 when the receiving end of the orthogonal magnetic coupling mechanism of the double flat spiral coils arranged based on the Fibonacci sequence is defined as k4; the coupling coefficient between the transmitting coil 1 and the receiving coil 1 when the receiving end of the orthogonal magnetic coupling mechanism of the double flat spiral coils arranged based on the Fibonacci sequence is defined as k5.

[0062] Figure 6 This chart compares the changing trends of the coupling coefficients k1 and k2 for a dual-panel spiral coil orthogonal magnetic coupling mechanism based on the Fibonacci sequence when offset along the X-axis. When the receiving end is offset within 200mm on the X-axis, the slope of k1 changes very little. This is because the self-inductance of the transmitting and receiving coils changes very little, and therefore their mutual inductance changes very little. This indicates that the coupling mechanism's transmitting coil 1 and receiving coil 1 are highly resistant to X-axis offset during energy transfer. However, k2 drops below 0.1 at an offset of 90mm, indicating slightly weaker X-axis offset resistance when transmitting and receiving coil 2. The Y-axis variation follows the same pattern as described above.

[0063] Figure 7 The following is a comparison chart of the coupling coefficient k1 variation trend when the double flat spiral coil orthogonal magnetic coupling mechanism arranged based on the Fibonacci sequence is offset along the X-axis and the coupling coefficient k3 variation trend between the transmitting coil 1 and the receiving coil 1 of the double flat spiral coil orthogonal magnetic coupling mechanism arranged at equal intervals. Figure 7The curves for k1 and k3 show that, as the receiving coil deflects more along the X-axis, the slope of the coupling coefficient k3 for the orthogonal magnetic coupling mechanism with evenly spaced double flat spiral coils changes slightly. However, the slope of the coupling coefficient k1 for the orthogonal magnetic coupling mechanism with evenly spaced double flat spiral coils changes even less than that of k3. This demonstrates that the orthogonal magnetic coupling mechanism with evenly spaced double flat spiral coils has stronger anti-deflection capability in the X-axis direction than the orthogonal magnetic coupling mechanism with evenly spaced double flat spiral coils. Similarly, the orthogonal magnetic coupling mechanism with evenly spaced double flat spiral coils has stronger anti-deflection capability in the Y-axis direction than the orthogonal magnetic coupling mechanism with evenly spaced double flat spiral coils.

[0064] Figure 8 This is a comparison chart showing the changing trends of the coupling coefficient k4 between the transmitting coil 1 and the receiving coil 1 when the receiving end of the orthogonal magnetic coupling mechanism of the double flat spiral coils arranged based on the Fibonacci sequence is rotated 45° around the Z axis and then offset along the X axis, and the coupling coefficient k5 between the transmitting coil 1 and the receiving coil 1 when the receiving end of the orthogonal magnetic coupling mechanism of the double flat spiral coils arranged at equal intervals is rotated 45° around the Z axis and then offset along the X axis.

[0065] By comparison Figure 7 and Figure 8 From the coupling coefficient values, it can be found that after the receiving coil rotates 45°, the coupling coefficients of the two mechanisms also increase accordingly. Figure 9 As shown in the magnetic field vector diagram of the receiving coil rotated 45°, when the receiving coil is rotated 45°, because the two transmitting coils are orthogonal, the same component a is generated on the X-axis and Y-axis of the receiving coil, and then superimposed on the receiving coil through the vector, so that the magnetic field strength of the receiving coil returns to the original value. times.

[0066] By comparison Figure 8 The curves for k4 and k5 show that, as the receiving coil deflects more along the X-axis, while the slope of the coupling coefficient k4 for the orthogonal magnetic coupling mechanism with equally spaced double flat spiral coils changes slightly, the slope of the coupling coefficient k5 for the orthogonal magnetic coupling mechanism with the Fibonacci sequence arrangement changes even less than that of k4. This demonstrates that the orthogonal magnetic coupling mechanism with the Fibonacci sequence arrangement has stronger anti-deflection capability in the X-axis direction after being rotated 45° about the Z-axis than the orthogonal magnetic coupling mechanism with equally spaced double flat spiral coils. Similarly, the orthogonal magnetic coupling mechanism with the Fibonacci sequence arrangement has stronger anti-deflection capability in the Y-axis direction after being rotated 45° about the Z-axis than the orthogonal magnetic coupling mechanism with equally spaced double flat spiral coils.

[0067] In summary, the Fibonacci double-helix coupling mechanism provided in this embodiment has two transmitting coils of the transmitting mechanism and two receiving coils of the receiving mechanism arranged orthogonally. Each coil is arranged based on the Fibonacci spacing to form a flat solenoid coil with a sparse center and dense sides. When horizontal or vertical offset or rotational offset occurs, the coupling coefficient only decreases moderately, and the mechanism has strong resistance to horizontal offset, vertical offset, and rotation. In addition, the coupling mechanism still has strong resistance to horizontal offset and vertical offset after rotation, and the mechanism as a whole has strong comprehensive anti-offset capability.

[0068] Example 2

[0069] In order to apply the Fibonacci double helix coupling mechanism of Example 1 to wireless power transmission, this embodiment provides a wireless power transmission system based on the Fibonacci double helix coupling mechanism, including a transmitting end and a receiving end. Figure 10 As shown, the transmitter includes a DC power supply V dc , a first high-frequency inverter and a second high-frequency inverter connected in parallel to a DC power supply, and also including a first transmitting coil L connected to the first high-frequency inverter P1 and a second transmitting coil L connected to a second high frequency inverter P2 The receiving end includes a first receiving coil L r1 , the second receiving coil L r2 , further comprising a first receiving coil L connected in series r1 Capacitor C r1 , connect the second receiving coil L in series r2 Capacitor C r2 , and connect capacitor C r1 The first rectifier filter circuit, connect capacitor C r2 The second rectifier and filter circuit is connected in parallel with the filter capacitor C of the first rectifier and filter circuit in series. L1 And the filter capacitor C of the second rectifier filter circuit L2 load circuit.

[0070] Current inverter topologies for wireless power transmitters primarily include full-bridge, half-bridge, and single-switch inverters. The first two are generally suitable for higher-power applications, but both suffer from complex control and peripheral circuitry, as well as issues like direct-pass bridge arms. In contrast, single-switch resonant inverter circuits offer advantages such as high reliability, simple control, low cost, and ease of achieving zero-voltage turn-on. Furthermore, advancements in power electronics have significantly improved the power capacity and withstand voltage of power semiconductors. Consequently, the limited power capacity of single-switch inverters is gradually being addressed.

[0071] The first high-frequency inverter and the second high-frequency inverter of this embodiment both adopt a single-tube high-frequency resonant inverter designed separately. The single-tube high-frequency resonant inverter includes an inductor Lf , capacitor C f , NMOS tube Q, capacitor C P , inductance L f , NMOS tube Q, capacitor C P Connect in series with the DC power supply V dc Between the positive and negative terminals, the source of the NMOS tube Q is connected to the inductor L f , drain connection capacitor C P The gate is used as the control terminal to connect the first PWM signal generator, and the capacitor C f Connected in parallel between the source and drain of the NMOS tube Q, the first transmitting coil L P1 Or the second transmitting coil L P2 (Uniformly represented as transmitting coil L P ) in parallel with the capacitor C P At both ends, the DC power supply V dc The negative terminal of the

[0072] In order to maintain good soft switching characteristics, the inductor L f With capacitor C f The input resonant angular frequency is between f satisfy:

[0073]

[0074] ∈[1.3,1.5] is the adjustment coefficient, and ω0 is the switching angular frequency of the NMOS tube Q.

[0075] In addition, in other embodiments, the position of the NMOS transistor Q and the capacitor C p The positions of the first transmitting coil L are swapped, and the first transmitting coil L P1 Or the second transmitting coil L P2 The position and capacitance C f Swap the positions.

[0076] As a specific and preferred embodiment, the NMOS transistor Q is an enhancement-type NMOS transistor, and the duty cycle of the NMOS transistor Q is set to A=0.5.

[0077] The operating modes of the single-switch high-frequency resonant inverter include:

[0078] 1) Mode between t0 and t1: At t0, the PWM signal is high, and the drain-source voltage V ds =0, NMOS tube Q realizes ZVS conduction, inductor L f The current I in , transmitting coil L p The current I Lprespectively decrease to zero; then, I Lp Start to increase positively, I in Starts to increase in the reverse direction, the capacitance C f Equivalent short circuit, V ds Keep it at zero;

[0079] 2) Mode between t1 and t2 :At t1, the PWM signal becomes low, the NMOS tube Q is turned off, and the inductor L f With capacitor C f , transmitting coil L p With capacitor C p start to resonate respectively; then, I Lp Start to decrease in the reverse direction, I in Starts to decrease in positive direction, V ds Start to increase positively;

[0080] 3) Mode between t2 and t3 :At t2, the PWM signal is continuously at low level, I Lp , I in Reduce to zero, V ds reaches its maximum value; then, I Lp Start to increase positively, I in Starts to increase in the reverse direction, V ds Start to decrease in positive direction;

[0081] 4) Mode between t3 and t4 : At t3, the PWM signal remains at a low level, I in Reaching the maximum value, I Lp Reaching the minimum value, V ds drops to zero, the inductance L f With capacitor C f , transmitting coil L p With capacitor C p End resonance; then, I Lp Starts to decrease in positive direction, I in Starts to decrease in the reverse direction, V ds Keep it at zero;

[0082] 5) Mode between t4 and t5 :At t4, the PWM signal becomes high level, due to the current flowing through the inductor L f The current is still negative, the NMOS tube Q is still in the off state, and the transmitting coil L p Continue forward discharge, when I Lp =0, enter the next switching cycle repeat mode .

[0083] In order to distinguish the first high frequency inverter from the second high frequency inverter, Figure 10 In the two single-tube high-frequency resonant inverters, the inductor, capacitor and other components with a subscript 1 correspond to the first high-frequency inverter, and the inductor, capacitor and other components with a subscript 2 correspond to the second high-frequency inverter.

[0084] The inverter has the characteristics of simple circuit structure, simple drive circuit, only one NMOS tube, and the resonance state is independent of the load. It can effectively achieve zero-voltage turn-on of the main switch in a wide load resistance range from rated load to short circuit. The system output voltage is approximately sinusoidal, and the total harmonic distortion of the system current is very small.

[0085] Although the orthogonal magnetic coupling mechanism of the double flat spiral coil has a strong anti-offset capability in the same plane, when the coupling mechanism is horizontally offset, the output voltage of the secondary rectifier will still change dramatically. In order to ensure the constant voltage output of the system, this paper adds a closed-loop Buck converter after the rectifier. Buck At 26~48V, it can achieve 24V constant voltage output, output power of 120W, and efficiency of up to 98.4%.

[0086] The load circuit of this embodiment includes an NMOS transistor Q3, a diode D5, an inductor L0, a capacitor C0, a load resistor R L , resistor R1, resistor R2, calculation module and drive circuit, filter capacitor C in series L1 and filter capacitor C L2 As a whole, it is regarded as a filter capacitor C L , the drain of NMOS tube Q3 is connected to the filter capacitor C L The source of NMOS tube Q3 is connected to the negative terminal of diode D5, and the positive terminal of diode D5 is connected to the filter capacitor C L The other end of the inductor L0 and the capacitor C0 are connected in series to the two ends of the diode D5, and the load resistor R L Connected to both ends of capacitor C0, resistors R1 and R2 are connected in series and then connected to both ends of capacitor C0. The calculation module is used to collect the voltage of resistor R1 or resistor R2 and calculate the PWM signal based on the voltage to act on the drive circuit. The drive circuit outputs the corresponding control signal to the gate of NMOS tube Q3.

[0087] The calculation module includes an ADC module, a filter, a PID controller, and a second PWM signal generator. The ADC module is used to collect the voltage of resistor R1 or resistor R2. The filter is used to perform median filtering using a bubble sort method to obtain a median voltage. The PID controller is used to obtain a calculated value through PID operation based on the median voltage and a reference voltage. The second PWM signal generator is used to generate a corresponding PWM signal from the calculated value and send it to the drive circuit.

[0088] In this example, the closed-loop control of the Buck circuit is realized by DSP TMS320F28027. The main program design flow chart is as follows: Figure 11 As shown in the figure, the ADC module is responsible for sampling the system's output voltage. Its sampling accuracy is 12 bits, and its maximum input voltage is 3V. Therefore, a voltage divider circuit with a 50:1 voltage divider ratio is required. The sampling interrupt is triggered by the PWM. When the time-base counter reaches CMPA, an A / D interrupt is triggered. This design reduces harmonics and avoids errors caused by output voltage jitter. Furthermore, to mitigate the impact of single-shot measurement errors, group filtering is introduced into the algorithm. This median filtering is performed using a bubble sort method to obtain the median voltage, which is then fed into the controller for computation. The PWM module operates in a continuous up / down counting mode. The time-base counter starts counting from 0. When it reaches the comparison value CMPA, the action module outputs a high level. The time-base counter then continues counting until it reaches a period match, switching to downcounting. When it reaches the comparison value CMPA again, the action module outputs a low level. When it reaches 0, it switches to upcounting, and so on. In this way, the PWM duty cycle can be controlled by controlling the comparison value CMPA.

[0089] Figure 10 The system equivalent circuit shown is Figure 12 As shown, it simplifies the analysis process. According to Kirchhoff's voltage law, Figure 12 The KCL and KVL equations of the equivalent model of the single-tube AC ​​circuit are shown in Equation (1), where the mutual inductance of the coupling mechanism is , .

[0090]

[0091] ω n is the resonant angular frequency of the system, which is equal to the switching angular frequency ω0 of the NMOS tube Q.

[0092] In this WPT system, to achieve tuning and matching between the primary winding and the secondary winding, the size of the compensation capacitor should meet the following requirements:

[0093]

[0094] f0 is the frequency corresponding to ω0.

[0095] Solving equation (2) yields The values ​​are:

[0096]

[0097] R o1 、R o2It is the equivalent resistance of the subsequent circuit in the two resonant circuits on the secondary side. r1 、R r2 is the inductance L r1 , L r2 The equivalent series resistance.

[0098] Therefore, the input impedance of the WPT system is:

[0099]

[0100] Therefore, the input power of the WPT system is:

[0101]

[0102] From formula (3), the output voltage of the rectifier circuit is They are:

[0103]

[0104] The solution is:

[0105]

[0106] From formula (7), we can see that V Buck With inductance L r , mutual inductance and load. When the load is determined, the inductance L can be reduced. r To increase V Buck , thereby reducing the input voltage level.

[0107] In addition, this example changes the excitation current (I in1 , I in2 ) Shift the phase by 180° to suppress the ripple of the input current and reduce the current stress of the DC power supply.

[0108] In order to verify the effectiveness and feasibility of the system, the proposed circuit model and control scheme are simulated and analyzed. A 120W WPT simulation model is built using MATLAB / Simulink software. The system switching frequency is 100kHz and the switch duty cycle is set to 0.5. The soft switching waveform of the NMOS tube Q is as follows: Figure 13 As shown, when the driving signal V gs Before the drain-source voltage V ds It has dropped to zero, indicating that the switch tube has achieved zero voltage turn-on. Figure 14Comparison of input current harmonic content. Comparing the input current waveforms before and after phase shifting, we can see that the harmonic content of the input current is smaller and the current is more stable after phase shifting. Buck At 26~48V, this system can maintain a constant voltage of 24V output within the range of ±70mm in the vertical and horizontal deviation when the air gap is 70mm, and the overall system efficiency is not less than 92%.

[0109] In summary, the embodiment of the present invention provides a wireless power transmission system based on the Fibonacci double-helix coupling mechanism, and its coupling mechanism adopts the Fibonacci double-helix coupling mechanism provided in Example 1, which has a high comprehensive anti-offset capability. The two high-frequency inverters adopt a dedicated single-tube high-frequency resonant inverter. The inverter has the characteristics of simple circuit structure, simple driving circuit, only one NMOS tube, and the resonant state is independent of the load. It can effectively realize the zero-voltage turn-on of the main switch in a wide load resistance range from rated load to short circuit. The system output voltage is approximately a sine wave, and the total harmonic distortion of the system current is very small. The receiving end adopts a closed-loop Buck converter after the rectifier to ensure that the system achieves constant voltage output. This example also shifts the excitation current of the two transmitting coils by 180° to suppress the ripple of the input current and reduce the current stress of the DC power supply. The constructed experimental prototype realizes that when V Buck When the voltage is between 26V and 48V and the air gap is 70mm, the constant voltage of 24V output is always maintained within the range of ±70mm in the vertical and horizontal deviation, and the overall system efficiency is not less than 92%.

[0110] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A wireless power transmission system based on a Fibonacci double helix coupling mechanism, characterized in that: The coupling mechanism of the system adopts a Fibonacci double helix coupling mechanism, which includes a transmitting mechanism and a receiving mechanism. The transmitting mechanism includes a first transmitting coil L P1 and the second transmitting coil L P2 The receiving mechanism includes a first receiving coil L r1 and the second receiving coil L r2 ; The first transmitting coil L P1 The winding method is: along the first direction, spirally winding based on the Fibonacci sequence interval from dense to sparse and then dense to form a flat block structure; The second transmitting coil L P2 The winding method is as follows: along a second direction orthogonal to the first direction, spirally winding the first transmitting coil L in a dense, sparse, and then dense manner based on the Fibonacci sequence interval. P1 superior; The first receiving coil L r1 The winding method is: spirally winding along the first direction based on the Fibonacci sequence interval first dense, then sparse, and then dense to form a flat block structure; The second receiving coil L r2 The winding method is: along the second direction, based on the Fibonacci sequence interval, the first receiving coil L is spirally wound densely, then sparsely, and then densely. r1 superior; The transmitting mechanism further includes a first flat block magnetic core, the first transmitting coil L P1 wound on the first flat block magnetic core; The receiving mechanism further includes a second flat block magnetic core, the first receiving coil L r1 wound on the second flat block magnetic core; The system includes a transmitting end; the transmitting end includes a DC power supply V dc , a first high-frequency inverter and a second high-frequency inverter connected in parallel to the DC power supply, and further comprising the first transmitting coil L connected to the first high-frequency inverter P1 and the second transmitting coil L connected to the second high frequency inverter P2 ; The first high-frequency inverter and the second high-frequency inverter both adopt a single-transistor high-frequency resonant inverter, and the single-transistor high-frequency resonant inverter includes an inductor L f , capacitor C f , NMOS tube Q, capacitor C P , the inductor L f , NMOS tube Q, capacitor C P Sequentially connected in series with the DC power supply V dc The source of the NMOS tube Q is connected to the inductor L between the positive and negative terminals. f , the drain is connected to the capacitor C P The gate is used as a control terminal for connecting to the first PWM signal generator, and the capacitor C f The first transmitting coil L is connected in parallel between the source and drain of the NMOS tube Q. P1 or the second transmitting coil L P2 In parallel with the capacitor C P At both ends of the DC power supply V dc The negative terminal of the 2. The wireless power transmission system based on the Fibonacci double helix coupling mechanism according to claim 1, characterized in that: The position of the NMOS tube Q and the capacitor C p The positions of the first transmitting coil L are swapped, and the first transmitting coil L P1 or the second transmitting coil L P2 The position of the capacitor C f Swap the positions.

3. The wireless power transmission system based on the Fibonacci double helix coupling mechanism according to claim 2, characterized in that: The inductor L f With the capacitor C f The input resonant angular frequency is between f satisfy: ， ∈[1.3,1.5] is the adjustment coefficient, and ω0 is the switching angular frequency of the NMOS tube Q.

4. The wireless power transmission system based on the Fibonacci double helix coupling mechanism according to claim 2 or 3, characterized in that: The system includes a receiving end; the receiving end includes the first receiving coil L r1 , the second receiving coil L r2 , further comprising connecting the first receiving coil L in series r1 Capacitor C r1 , connect the second receiving coil L in series r2 Capacitor C r2 , and connect the capacitor C r1 The first rectifier filter circuit is connected to the capacitor C r2 The second rectifier and filter circuit is connected in parallel with the filter capacitor C of the first rectifier and filter circuit connected in series. L1 and the filter capacitor C of the second rectifier filter circuit L2 load circuit.

5. The wireless power transmission system based on the Fibonacci double helix coupling mechanism according to claim 4, characterized in that: The resonant angular frequency ω of the system n It is equal to the switching angular frequency ω0 of the NMOS tube Q.

6. The wireless power transmission system based on the Fibonacci double helix coupling mechanism according to claim 5, characterized in that: The load circuit includes an NMOS tube Q3, a diode D5, an inductor L0, a capacitor C0, a load resistor R L , resistor R1, resistor R2, calculation module and drive circuit, filter capacitor C in series L1 and filter capacitor C L2 As a whole, it is regarded as a filter capacitor C L The drain of the NMOS tube Q3 is connected to the filter capacitor C L The source of the NMOS tube Q3 is connected to the negative terminal of the diode D5, and the positive terminal of the diode D5 is connected to the filter capacitor C L The other end of the inductor L0 and the capacitor C0 are connected in series and then connected to the two ends of the diode D5, and the load resistor R L connected to both ends of the capacitor C0, the resistor R1 and the resistor R2 are connected in series and then connected to both ends of the capacitor C0, the calculation module is used to collect the voltage of the resistor R1 or the resistor R2 and calculate the PWM signal based on the voltage to act on the drive circuit, and the drive circuit outputs the corresponding control signal to the gate of the NMOS tube Q3.

7. The wireless power transmission system based on the Fibonacci double helix coupling mechanism according to claim 6, characterized in that: The calculation module includes an ADC module, a filter, a PID controller, and a second PWM signal generator. The ADC module is used to collect the voltage of the resistor R1 or the resistor R2. The filter is used to perform median filtering using a bubble sort method to obtain a median voltage. The PID controller is used to obtain a calculated value through PID operation based on the median voltage and a reference voltage. The second PWM signal generator is used to generate a corresponding PWM signal from the calculated value and send it to the drive circuit.

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