Concave flat solenoid of wireless power transmission magnetic coupling mechanism

Abstract

The utility model discloses a concave flat solenoid of a wireless power transmission magnetic coupling mechanism, which comprises a first magnetic core integrally in a flat plate shape, auxiliary magnetic cores extending along the edge are arranged at two ends of the first magnetic core, and the auxiliary magnetic cores protrude upwards relative to the first magnetic core; the first magnetic core is provided with first coils wound in the length direction of the auxiliary magnetic cores, the first coils are distributed between the two auxiliary magnetic cores at intervals, and the protruding height of the first coils relative to the first magnetic core is smaller than that of the auxiliary magnetic cores. The solenoid structure has the advantages of being reasonable in structural design, high in adaptive capacity, low in implementation cost, capable of improving transmission efficiency and anti-offset capacity and the like.

Description

Technical Field

[0001] This utility model relates to the field of radio transmission technology, and in particular to a concave flat solenoid for a radio power transmission magnetic coupling mechanism. Background Technology

[0002] Inductive power transfer (IPT) is a cutting-edge power supply technology that utilizes near-field electromagnetic coupling to achieve non-physical contact power transfer. Compared to traditional plug-and-play charging, this technology effectively reduces the use of cables and offers advantages such as greater flexibility, lower maintenance costs, and higher safety. It has already been commercialized and is widely used in battery charging applications for electric vehicles, portable consumer electronics, intelligent unmanned systems, and medical electronic devices. However, these advantages are based on the premise that the primary and secondary coupling mechanisms are aligned correctly. In reality, the magnetic coupling mechanism inevitably experiences misalignment. After misalignment, the system's mutual inductance and coupling coefficient change significantly, leading to unstable power transmission, reduced efficiency, and a significant deterioration in system performance.

[0003] To improve the drift resistance of IPT systems, existing technologies mainly focus on adjusting control strategies, resonant topologies, or coupling mechanisms. In terms of control strategies, phase-shift control enhances the drift resistance of the IPT coupling mechanism, but the feedback signal from the receiver needs to be transmitted to the transmitter in real time, placing high demands on wireless communication. Using frequency conversion control can lead to an excessively large input impedance angle in the IPT system during control, resulting in excessive current stress at the transmitter and affecting system stability. This control method also places high demands on communication. Regarding compensation topologies, T / S, SP / S, S / SP, and LCC / S topologies have been proposed in recent years. The LCC / S topology inherits the advantages of the LCC / LCC topology while using fewer components, featuring constant input and output voltage and easy soft-switching. Although drift resistance can be improved through compensation topologies, the addition of too many resonant components increases the system order, increasing the difficulty of analysis. In coupling mechanism design, numerous studies have attempted to improve anti-offset performance by optimizing the structure of the coupling coils. To construct a uniform magnetic field and enhance the system's anti-offset capability, researchers have proposed coupling mechanisms such as bipolar (BP) coils, tripolar (TP) coils, solenoid (FSP) coils, double D-type (DD) coils, and double D-type orthogonal (DDQ) coils. Among these, the flat solenoid coil magnetic coupling mechanism exhibits superior anti-offset performance compared to planar circular and planar square magnetic coupling mechanisms. This has led to the development of other magnetic coupling mechanisms such as grid solenoids and zigzag solenoids, which also possess good anti-offset performance, but both their transmitter and receiver use square magnetic cores of the same size. However, this requirement for consistent core size cannot adapt to different application scenarios, and its implementation would significantly increase system costs. Utility Model Content

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by this utility model is: how to provide a concave flat solenoid for a wireless power transmission magnetic coupling mechanism with reasonable structural design, strong adaptability, low implementation cost, and improved transmission efficiency and anti-offset capability.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A magnetic coupling mechanism includes a transmitting solenoid, the transmitting solenoid including a first magnetic core that is generally flat, and two secondary magnetic cores extending along the edges at both ends of the first magnetic core, the secondary magnetic cores protruding upward relative to the first magnetic core; the first magnetic core has a first coil wound along the length direction of the secondary magnetic core, the first coils being distributed at intervals between the two secondary magnetic cores, and the protrusion height of the first coils relative to the first magnetic core being less than the protrusion height of the secondary magnetic cores.

[0007] In the above structure, since the first magnetic core has auxiliary magnetic cores at both ends and the thickness of the first coil is less than the height of the auxiliary magnetic core, the transmitting end solenoid can better gather the magnetic lines of force, and the receiving end has high transmission efficiency in the area above the first magnetic core. It has good anti-offset capability, strong adaptability, and does not require the transmitting end and the receiving end to use square magnetic cores of the same size, making it easy to implement.

[0008] Furthermore, the first coils are symmetrically distributed from the middle of the first magnetic core to both sides, and the distance between two adjacent first coils gradually decreases from the middle to both sides.

[0009] Furthermore, the distance between two adjacent first coils gradually decreases from the center to both sides in an arithmetic sequence.

[0010] Furthermore, the first coil is made of Litz wire.

[0011] In summary, the concave flat solenoid of this utility model has the advantages of reasonable structural design, strong adaptability, low implementation cost, and improved transmission efficiency and anti-offset capability. Attached Figure Description

[0012] Figure 1 This is the circuit topology diagram of the IPT system.

[0013] Figure 2 This is the LCC / S compensation topology diagram.

[0014] Figure 3 This is an equivalent model for LCC / S communication.

[0015] Figure 4 It is a traditional flat solenoid coil magnetic coupling mechanism.

[0016] Figure 5 The magnetic flux distribution is that of a traditional flat solenoid coil magnetic coupling mechanism.

[0017] Figure 6 This is an equivalent magnetic circuit model for a traditional flat solenoid magnetic coupling mechanism.

[0018] Figure 7 This is an improved flat solenoid coil magnetic coupling mechanism.

[0019] Figure 8 To design a flowchart.

[0020] Figure 9 For different launch institutions XY Planar magnetic flux density distribution diagram.

[0021] Figure 9 (a) is a conventional launching mechanism XY Planar magnetic flux density distribution diagram.

[0022] Figure 9 (b) Launch mechanism that only changes the winding method XY Planar magnetic flux density distribution diagram.

[0023] Figure 9 (c) A launching mechanism that only changes the shape of the magnetic core XY Planar magnetic flux density distribution diagram.

[0024] Figure 9 (d) is an improved launch mechanism XY Planar magnetic flux density distribution diagram.

[0025] Figure 9 (e) is a geometric series improved launch mechanism XY Planar magnetic flux density distribution diagram.

[0026] Figure 9 (f) is an improved launch mechanism based on the cumulative difference sequence. XY Planar magnetic flux density distribution diagram.

[0027] Figure 10 For an improved flat solenoid coupling mechanism YZ Planar magnetic induction intensity distribution diagram.

[0028] Figure 10 (a) shows the uniform distribution of magnetic induction intensity near the magnetic core.

[0029] Figure 10 (b) For the receiving end to Y Magnetic induction intensity distribution when offset by 15mm in the positive direction.

[0030] Figure 11 For different coupling mechanisms CCRR Schematic diagram of the change pattern.

[0031] Figure 11 (a) For the receiving end of different coupling mechanisms X When the axial direction is offset CCRR Schematic diagram of the change pattern.

[0032] Figure 11 (b) For the receiving end of different coupling mechanisms Y When the axial direction is offset CCRR Schematic diagram of the change pattern.

[0033] Figure 12 For different coupling mechanisms in XY A graph showing the variation of the plane offset coupling coefficient.

[0034] Figure 13 For the receiving end in X Comparison of system efficiency curves under directional offset conditions.

[0035] Figure 14 This is a comparison chart of system efficiency curves when the receiver is offset in the Y direction.

[0036] Figure 15 Waveform diagram of the experimental prototype of the improved coupling mechanism IPT system.

[0037] Figure 15 (a) is a waveform diagram of the inverter current and voltage when the receiver is facing the receiver.

[0038] Figure 15 (b) is a waveform diagram of the current and voltage before rectification at the receiving end in the facing state.

[0039] Figure 15 (c) is the receiving end at X Inverter current and voltage waveforms under a 30mm directional offset.

[0040] Figure 15 (d) is the receiving end at X Current and voltage waveforms before rectification when the direction is offset by 30mm.

[0041] Figure 15 (e) is the receiving end at Y Inverter current and voltage waveforms under a 15mm directional offset.

[0042] Figure 15 (f) is the receiving end at Y Current and voltage waveforms before rectification with a 15mm directional offset.

[0043] Figure 15 (g) is the receiving end at X Directional offset 15mm and Y Current and voltage waveforms before rectification with a 7mm directional offset.

[0044] Figure 15 (h) represents the receiving end at... X Direction offset 30mm and Y Current and voltage waveforms before rectification with a 15mm directional offset.

[0045] Figure 16 The waveforms of inverter voltage and transmitting coil current in the IPT system with improved coupling mechanism are shown.

[0046] Figure 16 (a) is a waveform diagram of the inverter voltage and the transmitting coil current when the receiver is facing the receiver.

[0047] Figure 16 (b) For the receiving end at X Waveforms of inverter voltage and transmitting coil current under a 30mm directional offset.

[0048] Figure 16 (c) is the receiving end at Y Waveforms of inverter voltage and transmitting coil current under a 15mm directional offset.

[0049] Figure 17 and Figure 18 The input voltages of the DC-DC converter during startup and surge are respectively. U L Output current I out and output voltage U out Waveform.

[0050] Figure 19 This is a diagram showing the system's output loss distribution. Detailed Implementation

[0051] The present invention will now be described in further detail with reference to a wireless power transmission system employing the present invention.

[0052] The wireless power transfer system in this embodiment enhances the system's anti-misalignment performance by modifying the structure of the flat solenoid transmitting magnetic core and the winding layout. An equivalent model of the LCC-S compensation circuit is established to analyze its output characteristics and derive the parameter configuration method for its resonant elements. Furthermore, a magnetomotive force model is established to analyze the coil magnetic field distribution characteristics, and finite element simulation reveals the magnetic field distribution patterns and coupling coefficient variations at different spatial locations of the mechanism. A 100W prototype is built to verify the effectiveness and feasibility of the proposed magnetic coupling mechanism.

[0053] System introduction and LCC / S compensation topology analysis: such as Figure 1 This is the circuit topology diagram of the IPT system, which consists of five parts: a full-bridge inverter, an LCC / S compensation topology, a loosely coupled transformer, a rectifier bridge, and a DC-DC converter. U dc Input DC voltage to the system; S 1~ S 4 represents a GaN switching transistor; U AB This is the equivalent input AC voltage after full-bridge inverter; L 1 represents the self-inductance of the transmitting coil; L 2 represents the self-inductance of the receiving coil; R 1 represents the internal resistance of the transmitting coil; R 2 represents the internal resistance of the receiving coil; L f To compensate for the inductance at the transmitting end; C f Parallel compensation capacitors are connected to the transmitting end; C 1 is the series compensation capacitor at the transmitting end; C 2 is a series compensation capacitor at the receiving end; R ab It is an equivalent resistive load; D It is a rectifier bridge; U ab This is the voltage before rectification; C d For output filter capacitors; R L For load resistance; U L This is the input voltage of the DC-DC converter. The DC-DC converter can achieve a constant voltage output of 20V and an output power of up to 100W.

[0054] The LCC / S type compensation topology used in this embodiment is as follows: Figure 2 As shown. This topology consists of a combination of LCC compensation at the transmitter and S-compensation at the receiver. When at the system operating frequency... f hour, L 2 and C2. Series resonance occurs. Since the LCC / S compensation network has good high-order filtering characteristics, the harmonic approximation method can be used for analysis. The LCC / S AC equivalent model is as follows: Figure 3 As shown.

[0055] When the system is in resonance, the input impedance can be determined from the LCC operating characteristics. Z in For purely resistive applications, the following relationship holds:

[0056] (1)

[0057] According to Kirchhoff's laws Figure 3 The KCL and KVL equations for the LCC / S circuit model are shown in equation (2):

[0058] (2)

[0059] We can obtain:

[0060] (3)

[0061] As can be seen from equation (3), the excitation current of the transmitting coil is only related to the compensation inductance and the AC input voltage, and is not related to the mutual inductance, self-inductance and load. The excitation current of the transmitting coil has constant current characteristics.

[0062] Rectified input voltage It can be represented as:

[0063] (4)

[0064] We can obtain:

[0065] (5)

[0066] Therefore, the system voltage gain G for:

[0067] (6)

[0068] From equation (6), it can be seen that the voltage gain G With equivalent load R ab Internal resistance of the receiving coil R 2. Transmitter compensation inductor L f and mutual induction M The output voltage of the receiving end has a constant voltage characteristic.

[0069] Magnetic Field Analysis of Coupling Mechanism: Considering the application scenarios of wireless charging, the transmitter's position is generally fixed, such as in electric vehicles, wireless charging of mobile phones, robots, and drones. The transmitter is less restricted by space and size, while the receiver's volume is generally limited by user needs and product size. Therefore, the receiver's volume is often smaller than the transmitter's. This not only reduces the amount of magnetic core used in the receiver but also lowers manufacturing costs and improves the flexibility of the receiver device. Based on this, most traditional flat solenoid coil coupling mechanisms are like... Figure 4 As shown, the device includes a transmitter and a receiver, both using ferrite cores of the same thickness. The length and width of the transmitter are twice that of the receiver. The transmitter core dimensions are 100mm × 50mm × 2.5mm, and the receiver core dimensions are 50mm × 25mm × 2.5mm. The air gap in the coupling mechanism is 10mm, and Litz wire is used. loose Winded around the ferrite core, along X The shafts are evenly spaced and arranged, which is a single magnetic flux direction structure, with only one magnetic flux loop in the cross-section of its magnetic core.

[0070] Figure 5 This diagram illustrates the magnetic flux distribution of a coupling mechanism constructed from a traditional flat solenoid coil. Unlike square or circular coil cores, which have a dual flux loop in their cross-section, the flat solenoid coupling mechanism does not exhibit opposing magnetic field lines in the main flux when the receiving end is offset. This avoids mutual cancellation and results in a slow decrease in the coupling coefficient. The dashed lines in the diagram represent the distribution of magnetic field lines in the coupling mechanism. The magnetic flux of the flat solenoid coupling mechanism mainly consists of self-coupling and mutual coupling components, with the mutual coupling component being the primary factor affecting mutual inductance and the coupling coefficient.

[0071] Depend on Figure 5 The magnetic flux distribution characteristics are analyzed, and magnetic reluctance is used to represent the magnetic flux distribution to construct... Figure 6 The equivalent magnetic circuit model is shown. The product of the excitation current and the number of turns of the transmitting and receiving coils determines the magnetomotive force of the circuit. Figure 6 middle, R m11 and R m12 Represents the self-coupling magnetoresistive element at the transmitting end. R m21 and R m22 This represents the self-coupling magnetoresistive at the receiving end, while R 12 This indicates mutual coupling magnetoresistive. Φ m1 For the self-coupling magnetic flux at the transmitting end, Φ m2 For the self-coupling portion of the magnetic flux at the receiving end, Φ 12That is the magnetic flux of the mutually coupled part. n 1 i 1 represents the magnetomotive force at the transmitting end. n 2 i 2 represents the magnetomotive force at the receiving end.

[0072] according to Figure 6 The equivalent magnetic circuit model of the traditional flat solenoid coupling mechanism includes the self-coupling magnetoresistance at the transmitting end. R m11 , R m12 and the self-coupling magnetoresistive element at the receiving end. R m21 , R m22 Perform the following processing:

[0073] (7)

[0074] (8)

[0075] Based on the equivalent magnetic circuit model of the coupling mechanism, the formulas for leakage inductance and coupling inductance are derived:

[0076] (9)

[0077] (10)

[0078] (11)

[0079] In summary, the coupling coefficient of the coupling mechanism can be obtained. k The value is:

[0080] (12)

[0081] From equation (12), it can be seen that the coupling coefficient k Only with self-coupling magnetoresistive R m1 , R m2 and mutual coupling magnetoresistance R 12 Related, reduce R 12 Or increase R m1 , R m2All of these factors can improve the coupling coefficient. The size, shape, winding distribution, and flux path of the magnetic core all affect the reluctance. Therefore, by optimizing the coil winding method, the flux and reluctance can be altered, thereby increasing the coupling coefficient. In summary, when the surface area of ​​the coil covering the magnetic core increases, the area of ​​the coupling portion increases, which helps reduce the reluctance of the leakage flux path, thus improving the coupling coefficient. Simultaneously, increasing the spacing between the coil windings increases the reluctance of the leakage flux path, which also improves the coupling coefficient.

[0082] Improved Flat Solenoid Coil Structure: To concentrate magnetic field lines and improve the coupling coefficient of the coupling mechanism, a large amount of Litz wire is often required, which not only increases the weight of the system but also significantly increases its cost. Therefore, this embodiment improves upon the traditional flat solenoid coil by designing a U-shaped ferrite core structure to concentrate the magnetic field lines and reconstructing the coil winding distribution, proposing an improved flat solenoid coil, such as... Figure 7 As shown in the figure, the receiving solenoid is located above the transmitting solenoid, and the solenoid includes a first magnetic core that is generally flat. At both ends of the first magnetic core are secondary magnetic cores extending along their edges, each secondary magnetic core protruding upwards relative to the first magnetic core. The first magnetic core has a first coil wound along the length of the secondary magnetic cores. These first coils are spaced apart between the two secondary magnetic cores, and the protrusion height of the first coil relative to the first magnetic core is less than the protrusion height of the secondary magnetic core. The first coils are symmetrically distributed from the center of the first magnetic core outwards, and the distance between two adjacent first coils gradually decreases from the center outwards.

[0083] To better compare the effects of different coupling mechanism parameters and anti-misalignment capabilities, a coupling coefficient retaining ratio is defined. CCRR )for:

[0084] (13)

[0085] In the formula: k 0 and k mis These are the coupling coefficients after the coupling mechanism is aligned and offset, respectively.

[0086] The design was simulated using the finite element method (FEM) software Ansys Maxwell. The determined core dimensions were 100mm × 50mm × 2.5mm for the transmitter and 50mm × 25mm × 2.5mm for the receiver. The air gap for the magnetic coupling mechanism was 10mm. The number of turns in the primary winding was also determined based on the core dimensions. N 1 is 15, the number of turns in the receiving end winding. N2 is 11, the offset of the receiving end relative to the original side is in X In the direction [-30mm, 30mm], with a step size of 5mm, in Y The direction is [-15mm, 15mm], with a step size of 3mm. The receiving-end windings are evenly spaced with a spacing of 0.1mm. The primary windings are non-uniformly arranged, with the winding spacing increasing arithmetically from both sides towards the middle, with a tolerance of [missing value]. d It has a dense pattern on both sides and a sparse pattern in the middle.

[0087] Record the self-inductance of the transmitting coil at each simulation point under the change of the transmitting coil spacing. L 1. Self-inductance of the receiving coil L 2 and mutual inductance M 12 After calculating the coupling coefficient, record it as a set of data, where the difference between the maximum and minimum values ​​is recorded as the range. R i This means that a smaller range indicates a smaller change in the coupling coefficient within the offset range, i.e., a stronger resistance to offset. By continuously optimizing the spacing, the offset can be reduced. R i This improves the anti-displacement capability of the coupling mechanism. The design flowchart is as follows: Figure 8 As shown, the specific steps are as follows:

[0088] S1, in Figure 7 Based on the structure shown, first determine the size, operating frequency, and air gap distance of the first and second magnetic cores;

[0089] S2. Based on the sizes of the first and second magnetic cores, determine the number of turns N1 of the first coil and the number of turns N2 of the second coil, and set the receiving solenoid relative to the transmitting solenoid at... X The offsets in the directional and Y directions and the simulation step size; the first coil and the second coil are arranged at equal intervals on the corresponding first magnetic core and the second magnetic core, respectively, as the initial state;

[0090] S3, in X Simulate the transmitter coil self-inductance in Maxwell within the offsets in the directional and Y directions according to the simulation step size. L 1. Self-inductance of the receiving coil L 2 and mutual inductance M 12 After calculating the coupling coefficient, the difference between the maximum and minimum values ​​is taken as the range. R i ;

[0091] S4, according to tolerance Arrange the spacing of the first coil from the center outwards in an arithmetic sequence, let... , For the previous business trip, In this embodiment, the tolerance step size is... The value is 0.04 mm; repeat step S3 to calculate the range. R i and the previous range R i-1 In comparison, if R i ≤ R i-1 Execute step S5; otherwise, let Repeat step S3 to calculate the range. R i and the previous range R i-1 In comparison, if R i ≤ R i-1 Proceed to step S5; otherwise, in Based on this, determine the tolerance for the next iteration and repeat step S4; during implementation, in and There will surely be one that satisfies the conditions. R i ≤ R i-1 .

[0092] S5, within tolerance The coupling coefficient is calculated. If the coupling coefficient meets the preset value, the tolerance of the first coil evenly distributed on the first magnetic core is determined as follows: Otherwise, repeat step S4.

[0093] The optimal parameter is selected based on the smallest change in coupling coefficient within the offset range. d =0.64, thus determining the specific coupling mechanism parameters.

[0094] Comparison with traditional flat solenoid coil structures: To further illustrate the anti-offset characteristics of the proposed coupling mechanism, simulation models of multiple magnetic coupling mechanisms were established using the finite element simulation software ANSYS MAXWELL, with winding method and core shape as variables. To ensure the validity of the comparison, the ferrite core material, number of turns, air gap distance, and Litz wire specifications were the same for all mechanisms, and the receiving end used flat solenoid coils with the same equidistant winding distribution.

[0095] Simulations were performed with only the transmitting mechanism being excited, without a receiver. Figure 9 Different launching mechanisms were displayed. XY The distribution of magnetic flux density in a plane, where, Figure 9 (a) is the traditional type. Figure 9(b) Change only the winding method Figure 9 (c) Only change the shape of the magnetic core. Figure 9 (d) is an improved form of arithmetic sequence. Figure 9 (d) is an improved geometric sequence. Figure 9 (e) is an improved form of the cumulative difference sequence. (Comparison) Figure 9 (a) and Figure 9 (b) The magnetic flux density of the traditional type is mainly concentrated in the middle of the core. Although its maximum magnetic flux density is slightly higher than that of the type that only changes the winding method, the magnetic flux density of the type that only changes the winding method is uniformly distributed across the entire plane; in contrast... Figure 9 (a) and Figure 9 (c) After changing the shape of the magnetic core, its overall magnetic flux density was greatly improved. The U-shaped structure formed by the magnetic core played a role in converging the magnetic lines of force. However, the magnetic flux density of both sides still showed a significant attenuation on the left and right sides. This uneven magnetic flux distribution is the main reason for the rapid decrease in the coupling coefficient when the receiving end of the coupling mechanism is offset. Figure 9 (a) and Figure 9 (d) The improved transmitting magnetic core has greatly improved both the magnetic flux density and the uniformity of magnetic flux distribution. This means that the coupling coefficient of the improved coupling mechanism will remain stable over a wide range during dynamic offset, and the descent speed will be relatively slow.

[0096] Figure 9 (e) Figure 9 (f) The magnetic flux density distribution at the transmitting end corresponds to the winding spacing arranged according to a geometric sequence and a cumulative difference sequence, respectively, and the core structure of both is altered. Due to the excessively dense windings on both sides, the magnetic field generated in space exhibits a double-hump shape, and it can be clearly seen from the figure that the magnetic flux density is concentrated on the left and right sides. Comparison Figure 9 As shown in (d), it is evident that the magnetic core with winding spacing arranged in an arithmetic sequence exhibits significantly better uniformity in magnetic flux density distribution than those arranged in a geometric or differential sequence. Therefore, these two mechanisms will not be analyzed further in subsequent simulations.

[0097] Figure 10 For an improved flat solenoid coupling mechanism YZ Planar magnetic field strength distribution diagram. When the coupling mechanism is facing upwards... Figure 10 (a) shows that the magnetic induction intensity near the magnetic core is uniformly distributed from left to right. Figure 10 (b) For the receiving end to Y The magnetic flux density distribution when offset by 15mm in the positive direction shows that the magnetic flux density distribution within the receiving end's magnetic core is denser on the left and sparser on the right, indicating that the magnetic flux is moving towards the right during the offset process. YNegative-direction aggregation, unlike planar square or planar circular coupling mechanisms, will slow down the increase of magnetic reluctance, thus making the decrease of coupling coefficient more slow. Traditional flat solenoid coupling mechanisms also have this characteristic, and this property is well continued in the improved coupling mechanism.

[0098] Different coupling mechanisms CCRR The pattern of change is as follows Figure 11 As shown, Figure 11 (a) Four coupling mechanisms are given at the receiver end. X When the axial direction is offset CCRR The changing pattern shows that when the offset reaches 30mm, the traditional coupling mechanism... CCRR The rate of decrease was the fastest, dropping to 0.656; only the winding method of the coupling mechanism was changed. CCRR Reduced to 0.789; only the core shape of the coupling mechanism was changed. CCRR The value dropped to 0.791; while the improved coupling mechanism CCRR It only dropped to 0.93, the rate of decline was slow, and it remained above 90%. Figure 11 (b) The receiving end of the four coupling mechanisms is... Y When the axial direction is offset CCRR The changes have led to the development of traditional flat solenoid coils, which already possess very outstanding characteristics. Y Directional anti-offset performance, although the four coupling mechanisms in Y When the axial direction is offset CCRR The changes are not significant, and both can maintain a high level, but the improved coupling mechanism still performs better.

[0099] Figure 12 Given XY The variation law of coupling coefficient of different coupling mechanisms in planar offset. X With the increase of shaft offset distance, the coupling coefficient of the improved coupling mechanism decreases at a rate of 0.003 / cm, which is less than the 0.016 / cm of the traditional type, less than the 0.008 / cm of the type that only changes the winding method, and less than the 0.01 / cm of the type that only changes the core shape. When the coupling mechanism... Y When the axial direction is offset, the rate of change of the coupling coefficient of different coupling mechanisms is 0.006 / cm for the traditional type, 0.004 / cm for the type that only changes the winding method, 0.005 / cm for the type that only changes the core shape, and 0.003 / cm for the improved type. The improved type still has the advantage. Based on the above comparison, it can be seen that the improved flat solenoid coupling mechanism has the best anti-offset performance.

[0100] Experimental Verification: To verify the anti-offset performance of the IPT system, an experimental prototype test platform was built. The parameters of the IPT system prototype are shown in Table 1. The debugging equipment shown in the figure mainly includes a DC power supply, auxiliary power supply, voltage probe, current probe, oscilloscope, and electronic load. The IPT system mainly consists of a full-bridge inverter circuit, a compensation mechanism, a rectifier bridge, and a DC-DC circuit. In addition, two coupling mechanisms, a traditional type and an improved type, were wound based on a flat solenoid coil. The air gap distance between the transmitting and receiving ends of the coupling mechanism is 10 mm.

[0101] Table 1 System Basic Parameters

[0102] Parameters or components numerical value or model number <![CDATA[Input voltage U dc / V]]> 100 Switching frequency / kHz 200 Primary-side controller MCU STM32G030F6P6 <![CDATA[Power switching transistor S 1- S 4]]> GS66508T <![CDATA[Rectifier diode D 1- D 4]]> SB1045L <![CDATA[DC-DC switching transistor D 5- D 6]]> CSD19534Q5A <![CDATA[Load R L / Ω]]> 4

[0103] Table 2 Parameters of Traditional Coupling Mechanism

[0104] parameter Numerical <![CDATA[Emitter compensation inductor L f / μH]]> 10.2 <![CDATA[Parallel compensation capacitor at the transmitting end C f / nF]]> 65.3 <![CDATA[Series compensation capacitor at the transmitting end C 1 / nF]]> 44.4 <![CDATA[Self-inductance of the transmitting coil L 1 / μH]]> 14.3 Coil mutual inductance / μH 2.4 <![CDATA[Receiving-end compensation capacitor C 2 / nF]]> 43.5 <![CDATA[Self-inductance of the receiving coil L 2 / μH]]> 13.7 <![CDATA[Internal resistance of the transmitting coil R 1 / mΩ]]> 89.2 <![CDATA[Internal resistance of receiving coil R 2 / mΩ]]> 16

[0105] Table 3 Parameters of the Improved Coupling Mechanism

[0106] parameter Numerical <![CDATA[Transmitter compensation inductor L f / μH]]> 9.8 <![CDATA[Parallel compensation capacitor at the transmitting end C f / nF]]> 63.8 <![CDATA[Series compensation capacitor at the transmitting end C 1 / nF]]> 46.7 <![CDATA[Self-inductance of the transmitting coil L 1 / μH]]> 23.1 Coil mutual inductance / μH 3.2 <![CDATA[Receiving-end compensation capacitor C 2 / nF]]> 43.5 <![CDATA[Self-inductance of receiving coil L 2 / μH]]> 13.7 <![CDATA[Internal resistance of the transmitting coil R 1 / mΩ]]> 25 <![CDATA[Internal resistance of the receiving coil R 2 / mΩ]]> 16

[0107] Figure 13 and Figure 14 This study compares the system efficiency curves of a traditional coupling mechanism and an improved coupling mechanism. The results show that the system efficiency of the traditional coupling mechanism is 91.4% when the receiver is directly aligned; when the receiver is aligned with the improved coupling mechanism... X When the direction is offset by 30mm, the efficiency drops to 60.5%; along the Y When the direction is offset by 15mm, the efficiency drops to 80.6%. This significant decrease in efficiency is due to the rapid decrease in the coupling coefficient of the conventional flat solenoid coil coupling mechanism when the horizontal position is offset.

[0108] In comparison, the system efficiency is 89.3% when the receiver of the improved coupling mechanism is directly aligned; when along... X When the direction is offset by 30mm, the efficiency is 83.1%; along the Y When the direction is offset by 15mm, the efficiency is 85.6%; the system built based on the improved coupling mechanism... X , Y The system efficiency remained above 83% even with directional deviation. Experimental results are consistent with those of the two coupling mechanisms. CCRR The simulation results of the relationship between the displacement and the change are basically consistent, which verifies the superior anti-displacement capability of the proposed improved coupling mechanism.

[0109] exist Figure 15 The waveform diagrams for the experimental prototype of the improved coupling mechanism IPT system include those of the receiving end at the alignment point. X Direction offset Y Directional offset andX , Y The main operating waveforms of the system under simultaneous directional offset, including the inverter's output voltage. U AB and inverter output current I AB Input voltage before rectification at the receiving end U ab Input current before rectification I 2. The DC input voltage remains at 100V regardless of the location of the load. R L =4. Experimental results show that under different offset conditions, the inverter output voltage and current have small phase differences, the system impedance is biased towards inductance, and the switching devices can always be in ZVS state to achieve soft switching, enabling the system to achieve efficient energy transfer. Figure 15 (g) and Figure 15 (h) gives the system when it occurs X , Y Comparison of voltage and current before rectification when both directions deviate simultaneously. Figure 15 (b) The waveform at the initial position shows that the rate of change of voltage and current after offset does not exceed 5%, which can be approximated as a constant output of the system, verifying the system's performance. XY The anti-offset performance of the plane.

[0110] Figure 16 For the improved coupling mechanism of the IPT system receiver, the alignment and... X Positive offset 30mm and Y The inverter voltage and transmitter coil excitation current waveforms of the system under three different positions with a positive directional offset of 15mm are shown. Experimental results indicate that the transmitter coil excitation current under the three different positions... I 1. Always with the inverter output voltage U AB Maintaining a 90° phase difference throughout, and with the transmitting coil excitation current in three different positions... I The amplitudes are approximately equal, consistent with the theoretical derivation of equation (3), reflecting the transmission characteristics of the LCC / S compensation topology.

[0111] The improved coupling mechanism proposed in this embodiment has excellent anti-offset performance. At the same time, in order to ensure the constant output voltage, a DC-DC converter capable of achieving a wide input range of 22~55V and a constant output of 20V is added to the front end of the load side, with a maximum efficiency of 96%. Figure 17 and Figure 18 The input voltages of the DC-DC converter during startup and surge are respectively. U L Output current I out and output voltage Uout Waveform, Figure 17 middle, U L A jump from 0V to 25V, Figure 18 middle, U L The voltage suddenly increases from 25V to 50V. As shown in the figure, the converter's output voltage and current can be well tracked in both processes, and it has a fast response speed, demonstrating the good static and dynamic performance of the DC-DC converter.

[0112] The constructed IPT system operated continuously for 20 minutes under rated conditions. The system thermal imaging showed that the maximum system loss originated from the rectifier bridge, which still reached 42.6℃ even with heat sinks installed. The second largest loss was from the coupling mechanism, regardless of whether it was directly aligned or experiencing other issues. X , Y The direction of the magnetic core deflection is relatively stable, mainly concentrated at the center of the transmitting core, with a maximum temperature of 56.2℃. This temperature rise is caused by hysteresis loss and eddy current loss. The receiving core temperature is much lower than the transmitting end, not exceeding 30℃. When the system is in long-term operation, the primary side needs to choose a reasonable heat dissipation method. Due to its small size and low heat loss, the receiving core does not require an additional heat dissipation device, making it more suitable for implantation in mobile and portable devices such as mobile phones and drones. Furthermore, the excellent anti-deflection performance of this coupling mechanism broadens its application prospects. The losses of the compensation mechanism, inverter, and DC-DC converter are relatively small. Other losses exist, including line losses and circuit modeling deviations. The specific system output loss distribution is as follows: Figure 19 Further research will continue to improve and optimize efficiency.

[0113] This embodiment presents an improved flat solenoid coil wireless power transmission system. It employs an improved flat solenoid magnetic coupling mechanism and an LCC-S compensation network topology, effectively enhancing the system's anti-offset characteristics. The optimization method for the magnetic coupling mechanism parameters and the parameter configuration conditions for the LCC-S compensation network are provided. When the prototype receiver is offset within ±50° in the X and Y directions, the system output voltage fluctuation rate remains within 5%, and the transmission efficiency reaches over 89%, verifying the effectiveness and feasibility of the proposed system.

[0114] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A concave flat solenoid for a wireless power transmission magnetic coupling mechanism, characterized in that, The device includes a first magnetic core that is generally flat, and two auxiliary magnetic cores that extend along the edges at both ends of the first magnetic core. The auxiliary magnetic cores protrude upward relative to the first magnetic core. The first magnetic core has a first coil wound along the length direction of the auxiliary magnetic cores. The first coils are distributed at intervals between the two auxiliary magnetic cores, and the protrusion height of the first coils relative to the first magnetic cores is smaller than the protrusion height of the auxiliary magnetic cores. The first coils are symmetrically distributed from the middle of the first magnetic core to both sides, and the distance between two adjacent first coils gradually decreases from the middle to both sides; The distance between two adjacent first coils gradually decreases from the middle to both sides in an arithmetic sequence.

2. The concave flat solenoid of the wireless power transmission magnetic coupling mechanism as described in claim 1, characterized in that, The first coil is made of Litz wire.

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