Multi-angle anti-deviation underwater MC-WPT system based on spherical cap double D-type coil

Abstract

The present invention relates to the technical field of underwater wireless power transmission, and specifically discloses a multi-angle anti-deviated underwater MC-WPT system based on a spherical cap double D-type coil. The system designs a spherical cap double D-type coil coupling mechanism and designs appropriate coupling mechanism parameters, and designs a primary and secondary side resonant network and designs appropriate resonant network parameters, so that when there is a large angle rotation offset at the receiving end in three-dimensional space, the mutual inductance of the coupling mechanism changes less, and the output power and efficiency of the system can meet the design requirements. Taking a wireless charging system with an output power of not less than 3kW and a system efficiency of not less than 85% as an example, the present invention uses COMSOL modeling to analyze the change of mutual inductance between the transmitting end and the receiving end when there is an offset in three-dimensional space, and the mutual inductance change rate is small. The present invention also verifies through MATLAB / Simulink simulation that the system can still maintain an output power of 3kW with small fluctuations when the mutual inductance changes, and the output efficiency is not less than 85%.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater wireless power transmission, and in particular to a multi-angle anti-deviating underwater MC-WPT system based on a spherical cap double D-type coil. Background Art

[0002] Faced with the complex marine environment, underwater inspection robots are increasingly widely used. They can replace manual operations in the open ocean, deep sea and dangerous waters to perform tasks, and are used for underwater environment operation and maintenance inspections. They can detect potential risks such as exposed, displaced, suspended, and bent submarine cables in advance, and quickly locate faults when serious faults occur. However, their endurance is a major problem that needs to be solved urgently. At present, the conventional wired charging method requires a special charging interface to be set on the outside of the underwater inspection robot body, which will affect the overall waterproofness and sealing of the robot. In addition, frequent plugging and unplugging of the charging connector is prone to mechanical wear and safety issues. Therefore, seeking a safe, convenient and intelligent way to replenish electricity has become a problem that must be solved in the development process of such underwater inspection robots. Wireless power transmission (WPT) technology, as a new charging method, is safe and convenient. It no longer requires expensive sealing devices such as wet plug interfaces to isolate from the water environment. At the same time, it can realize the replenishment of electricity under working conditions, which improves the endurance of underwater inspection robots.

[0003] Wireless Power Transfer (WPT) technology is a technology that uses theories and technologies such as power electronics and control to transmit electric energy from a power grid or battery to electrical equipment in a non-electrical contact mode through a carrier (such as electric field, magnetic field, microwave, laser, etc.). The most commonly used method is magnetically coupled wireless power transfer technology (MC-WPT), which uses the coupling magnetic field between the transmitting coil and the receiving coil as a carrier to achieve the transmission of electric energy. At present, magnetic field coupled wireless power transfer technology has been widely used in various fields, such as marine robots, electric vehicles, oil extraction, etc.

[0004] In the application of MC-WPT technology in marine robots, due to the complex marine environment, when the marine equipment is replenishing power, unpredictable situations such as seabed surges will cause the underwater inspection robot to shake, resulting in a certain degree of offset between the transmitter and the receiver of the MC-WPT system in three-dimensional space, affecting the output performance. Therefore, it is necessary that the MC-WPT system can still maintain good charging performance, the output power can still meet the demand, and the output efficiency can be maintained at a high level when there is an offset between the transmitter and the receiver in three-dimensional space. Summary of the invention

[0005] The present invention provides a multi-angle anti-offset underwater MC-WPT system based on a spherical cap double D-type coil, and solves the technical problem of how to ensure that the MC-WPT system can still maintain good charging performance, the output power can still meet the demand, and the output efficiency can be maintained at a high level when there is an offset between the transmitting end and the receiving end in three-dimensional space.

[0006] In order to solve the above technical problems, the present invention provides a multi-angle anti-deviated underwater MC-WPT system based on a spherical cap double D-type coil, including a transmitting end and a receiving end, wherein the transmitting end includes a DC power supply, a high-frequency inverter, a primary compensation network, and a transmitting coil connected in sequence, and the receiving end includes a receiving coil, a secondary compensation network, a rectifier filter circuit, and a load connected in sequence. The key is:

[0007] The transmitting coil adopts a spherical cap arc of β and a large circle radius of r dp , wire diameter is r p , the number of turns is N p The first spherical cap double D-type coil is formed by connecting the symmetrical first D-type coil at the transmitting end and the second D-type coil at the transmitting end in opposite directions; the receiving coil adopts a spherical cap with a radian of β and a large circle radius of r ds , wire diameter is r s , the number of turns is N s The second spherical cap double D-type coil is formed by connecting a symmetrical first D-type coil at the receiving end and a second D-type coil at the receiving end in series in opposite directions; the distance between the transmitting coil and the receiving coil, that is, the wireless transmission distance, is d;

[0008] The transmitting end is also provided with a transmitting end magnetic core matching the shape of the transmitting coil, and the receiving end is also provided with a receiving end magnetic core matching the shape of the receiving coil. The thickness of the transmitting end magnetic core and the receiving end magnetic core are both H c .

[0009] Preferably, the transmitting coil, the transmitting end magnetic core, the receiving coil, and the receiving end magnetic core form a coupling mechanism, and the parameters of the coupling mechanism are determined by the following steps:

[0010] A1. Determine r according to design requirements dp 、r ds ,β,d;

[0011] A2. Determine the wire diameter r of the primary and secondary coils based on the system power and the primary and secondary coil currents p 、r s ;

[0012] A3. Determine the core thickness H based on the self-inductance and mutual inductance requirements and engineering experience c ;

[0013] A4. Set the number of turns of the original secondary coil N p =1, N s =1;

[0014] A5. Simulate and calculate the self-inductance L of the transmitting coil when the coupling mechanism is offset p , the self-inductance L of the receiving coil s , the mutual inductance M between the transmitting coil and the receiving coil in the underwater environment wat ;

[0015] A6. Determine the mutual inductance M wat Whether the change meets the anti-drift requirement, if so, the output is the various parameters L of the coupling mechanism p , L s 、N p 、N s 、M wat , if otherwise the original secondary turns N p 、N s Add 1 successively and return to step A5.

[0016] Preferably, the primary compensation network is an LCC type compensation structure, including a compensation inductor L pr , parallel compensation capacitor C p1 And series compensation capacitor C p2 ;

[0017] The secondary side compensation network is an S-type series compensation structure, including a compensation capacitor C s .

[0018] Preferably, the parameters of the primary compensation network and the secondary compensation network are determined by the following steps:

[0019] B1. Determine the system output power P according to the design requirements and the rated power level of the underwater inspection robot. out , transmission efficiency η, operating frequency f, load resistance R L , output voltage U out ;

[0020] B2. Comprehensively consider the system voltage resistance, current resistance, power and efficiency factors to determine the system input DC voltage U in ;

[0021] B3, according to COMSOL software simulation, L p , L s 、M wat , R p , R s , R p is the internal resistance of the transmitting coil R p1 Equivalent resistance R to eddy current loss at the transmitting end p2The sum, R s is the internal resistance of the receiving coil R s1 The equivalent resistance R of the eddy current loss at the receiving end s2 sum;

[0022] B4, by U out ≥(M wat(min) / L pr ) in The system resonance parameter L is obtained by the system resonance relationship pr , C p1 , C p2 , C s , M wat(min) It represents the minimum value of mutual inductance when the coupling mechanism is offset;

[0023] B5. Simulation calculation U out , P out Does it meet the requirements? If yes, go to the next step. If not, follow the U out ≥(M wat(min) / L pr ) in Modify L pr And recalculate U out , P out Until the requirements are met;

[0024] B6. Simulate and calculate whether η meets the requirements. If so, output the resonance parameters L of each system. pr , C p1 , C p2 , C s If not, adjust U in Return to step B4.

[0025] Preferably, in step B4, the system resonance relationship is expressed as:

[0026]

[0027] ω0=2πf represents the operating angular frequency of the system.

[0028] Preferably, the transmitting coil and the receiving coil are both wound in a single layer. dp =r ds , N p =N s , r p >r s .

[0029] Preferably, the receiving coil and the receiving end magnetic core are installed on the upper wall of the contained underwater inspection robot, and the transmitting coil and the transmitting end magnetic core are installed in a horn-type docking station. The contained underwater inspection robot enters the docking station, and the transmitting end charges the contained underwater inspection robot.

[0030] Preferably, the high frequency inverter adopts a full-bridge inverter circuit composed of switching devices S1, S2, S3, and S4.

[0031] Preferably, the rectifier and filter circuit adopts a rectifier bridge and a filter capacitor C f The rectifier bridge adopts a full-bridge rectifier composed of diodes D1, D2, D3, and D4.

[0032] The invention provides a multi-angle anti-deviating underwater MC-WPT system based on a spherical cap double D-type coil, which has the following beneficial effects:

[0033] The present invention designs a spherical cap double D-type coil coupling mechanism and designs appropriate coupling mechanism parameters, and designs the primary and secondary side resonant network and designs appropriate resonant network parameters, so that when the receiving end has a large angle rotation offset in three-dimensional space, the mutual inductance of the coupling mechanism changes less, and the output power and efficiency of the system can meet the design requirements. Taking a wireless charging system with an output power of not less than 3kW and a system efficiency of not less than 85% as an example, the present invention uses COMSOL modeling to analyze the change of mutual inductance between the transmitting end and the receiving end when there is an offset in three-dimensional space, and the mutual inductance change rate is small. The present invention also verifies through MATLAB / Simulink simulation that the system can still maintain an output power of 3kW with small fluctuations when the mutual inductance changes, and the output efficiency is not less than 85%, thereby verifying the correctness and effectiveness of the system and parameter design method proposed by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a stereoscopic diagram of a spherical cap double D-shaped coupling mechanism provided by an embodiment of the present invention;

[0035] Figure 2 is a magnetic field distribution diagram of a spherical cap double D-type coupling mechanism provided by an embodiment of the present invention;

[0036] Figure 3 : is an equivalent magnetic circuit diagram of a spherical cap double D-type coupling mechanism provided by an embodiment of the present invention;

[0037] Figure 4 is a coil offset model diagram provided by an embodiment of the present invention;

[0038] Figure 5 is a parameter design flow chart of a coupling mechanism provided by an embodiment of the present invention;

[0039] Figure 6 It is a topological diagram of a multi-angle anti-drift underwater MC-WPT system provided by an embodiment of the present invention;

[0040] Figure 7 is a mutual inductance model diagram of the LCC-S type MC-WPT system provided by an embodiment of the present invention;

[0041] Figure 8 : is a structural diagram of a spherical cap double D-type coupling mechanism provided by an embodiment of the present invention: (a) front view, (b) side view;

[0042] Fig. 9 This is a schematic diagram of charging and docking of an inspection robot provided by an embodiment of the present invention;

[0043] Fig.10 This is a schematic diagram of a receiving end rotating and offsetting along the X-axis provided by an embodiment of the present invention;

[0044] Fig.11 It is a schematic diagram of the Y-direction offset of the receiving end provided by an embodiment of the present invention;

[0045] Fig.12 This is a schematic diagram of the X-direction offset of the receiving end provided by an embodiment of the present invention;

[0046] Fig.13 This is a schematic diagram of a receiving end rotating and offsetting along the Y axis provided by an embodiment of the present invention;

[0047] Fig.14 This is a schematic diagram of a receiving end provided by an embodiment of the present invention rotating about the Z axis;

[0048] Fig.15 is a schematic diagram of a double U-shaped coupling mechanism provided by an embodiment of the present invention;

[0049] Fig.16 is a schematic diagram of a flat double-D coupling mechanism provided by an embodiment of the present invention;

[0050] Fig.17 is a schematic diagram of rotational offset of a spherical cap type coupling mechanism provided by an embodiment of the present invention;

[0051] Fig.18 is a comparison diagram of the mutual inductance change rates of different coil rotation offsets provided by an embodiment of the present invention;

[0052] Fig.19 is a flow chart of system circuit parameter design provided by an embodiment of the present invention;

[0053] Fig. 20 It is an inverter waveform diagram of a closed-loop system when the coupling mechanism provided by an embodiment of the present invention is facing in the positive direction;

[0054] Fig.211 is a diagram showing changes in system efficiency and power when the receiving end is rotated and offset according to an embodiment of the present invention: (a) efficiency, (b) power;

[0055] Fig. 22 1 is a diagram showing changes in system efficiency and power when the receiving end is offset in the Y direction provided by an embodiment of the present invention: (a) efficiency, (b) power. DETAILED DESCRIPTION

[0056] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood 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 patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0057] For a single-coil coupling mechanism, when there is an offset between the transmitter and the receiver, only a portion of the magnetic field excited by the transmitter coil couples with the receiver coil, and a large amount of magnetic field is distributed in the surrounding space, which reduces the coupling degree between the primary and secondary sides and affects the transmission performance. The current directions in the two loops of the DD-type coil are opposite, and different magnetic field distribution characteristics of a single planar coil will appear, that is, the magnetic lines of force start from one side of the loop and end at the other side, forming a closed magnetic flux loop inside the magnetic coupling mechanism. The DD-type coil distributes the magnetic field as much as possible inside the magnetic coupling mechanism, reducing leakage magnetic flux and enhancing the system's anti-offset performance.

[0058] When both the transmitter and receiver are DD coils, due to the special winding method of the DD coil, when the two are facing each other, there are two loops at the receiver, and the effective magnetic flux will increase. The effective magnetic flux effects of the two loops are superimposed, and the induced voltage will increase significantly compared to the case of a single flat coil at the receiver.

[0059] At present, the docking and charging method of the inclusive underwater inspection robot is:

[0060] The receiving end is placed inside the underwater inspection robot. After the underwater inspection robot enters the charging area, the transmitting end located in the docking station charges the underwater inspection robot. Due to the existence of underwater surges, the underwater inspection robot will deflect to a certain extent when entering the docking station, resulting in an offset between the transmitting end and the receiving end, causing a change in mutual inductance. Therefore, the underwater WPT system is required to have a certain anti-offset capability in three-dimensional space, and when the coupling mechanism is offset in three-dimensional space, the change in mutual inductance should be suppressed as much as possible.

[0061] In view of the above problems, the transmitting coil and the receiving coil of the present invention both adopt spherical cap double D-type coils, such as Figure 1 As shown, the anti-deviation capability is strong. Specifically, the transmitting coil adopts a spherical cap curvature of β and a large circle radius of r dp , wire diameter is rp , the number of turns is N p The first spherical cap double D-type coil is composed of a symmetrical first D-type coil at the transmitting end and a second D-type coil at the transmitting end connected in series in opposite directions; the receiving coil adopts a spherical cap with a radian of β and a large circle radius of r ds , wire diameter is r s , the number of turns is N s The second spherical cap double D-type coil is formed by connecting the symmetrical first D-type coil at the receiving end and the second D-type coil at the receiving end in series in opposite directions; the distance between the transmitting coil and the receiving coil, that is, the wireless transmission distance, is d. For this coupling mechanism, the transmitting end is also provided with a transmitting end magnetic core that matches the shape of the transmitting coil, and the receiving end is also provided with a receiving end magnetic core that matches the shape of the receiving coil. The thickness of the transmitting end magnetic core and the receiving end magnetic core are both H c .

[0062] By establishing a spherical cap double D-type coil model in COMSOL simulation software, the magnetic field distribution of the XZ section of the spherical cap double D-type coil is obtained as follows: Figure 2 shown. Figure 2 The middle arrows represent magnetic lines of force. According to the magnetic field distribution of the spherical cap double D-type coil, the magnetic flux of the air gap is divided into mutual coupling flux and leakage flux, and the magnetic flux generated by the spherical cap double D-type coil is divided into 4 self-coupling regions and 2 mutual coupling regions. The magnetic resistance of mutual coupling region 1 and mutual coupling region 2 are R m1 and R m2 , Φ m1 , Φ m2 is the magnetic flux of mutual coupling region 1 and mutual coupling region 2; Φ s1 , Φ s2 , Φ s3 , Φ s4 is the magnetic flux of self-coupling region 1, self-coupling region 2, self-coupling region 3 and self-coupling region 4, and the magnetic resistance of self-coupling region 1, self-coupling region 2, self-coupling region 3 and self-coupling region 4 is R s1 , R s2 , R s3 and R s4 F1 is the magnetomotive force generated by the D coil on the left side of the transmitting coil, and F2 is the magnetomotive force generated by the D coil on the right side of the transmitting coil. The left coil and the right coil of the spherical cap double D-type coil are connected in series, so F1 and F2 are approximately equal in size but opposite in direction. In summary, the equivalent magnetic circuit model of the spherical cap double D-type coil can be obtained, as shown in Figure 3 shown.

[0063] Depend on Figure 3 Equivalent magnetic circuit, the expressions of leakage flux and mutual coupling flux can be obtained as:

[0064]

[0065] For the coupling coefficient k, we have:

[0066]

[0067] Since the two D coils of the transmitting coil are wound by the same wire, F1 and F2 are approximately equal in size. Since the transmitting coil is a symmetrical structure, it can be considered that R s3 and R s4 Substituting formula (1) into formula (2) yields:

[0068]

[0069] Among them, in order to simplify the expression of k, the parameters customized

[0070] It can be seen from the above formula that the coupling coefficient of the spherical crown double D-type magnetic coupling mechanism is positively correlated with the magnetic permeability of the magnetic circuit in the mutual coupling area, and negatively correlated with the magnetic permeability of the magnetic circuit in the self-coupling area. Therefore, the coupling coefficient can be improved by reasonably selecting coil parameters, magnetic core structure and optimizing the magnetic resistance of the magnetic circuit in each coupling area.

[0071] In order to illustrate the relationship between the parameters of the magnetic coupling mechanism and the mutual inductance, taking two parallel coils as an example, by establishing the offset model of the transmitting coil and the receiving coil, the relationship between the mutual inductance and the coil orientation between the transmitting coil and the receiving coil is obtained, as shown in Figure 4 shown.

[0072] In summary, assuming that the radius of the transmitting coil is r dp , the radius of the receiving coil's large circle is r ds , the spherical crown curvature is β, the transmission distance is d; the transmitting coil wire diameter is r p , the receiving coil wire diameter is r s The number of turns of the transmitting coil is N p , the number of turns of the receiving coil is N s , the core thickness is H c , the coupling mechanism design process is as follows Figure 5 As shown, the specific steps include:

[0073] A1. Determine r according to design requirements dp 、r ds ,β,d;

[0074] A2. Determine the wire diameter r of the primary and secondary coils based on the system power and the primary and secondary coil currents p 、r s ;

[0075] A3. Determine the core thickness H based on the self-inductance and mutual inductance requirements and engineering experience c ;

[0076] A4. Set the number of turns of the original secondary coil N p =1, N s =1;

[0077] A5. Simulate and calculate the self-inductance L of the transmitting coil when the coupling mechanism is offset p , the self-inductance L of the receiving coil s , the mutual inductance M between the transmitting coil and the receiving coil in the underwater environment wat ;

[0078] A6. Determine the mutual inductance M wat Whether the change meets the anti-drift requirement, if so, the output is the various parameters L of the coupling mechanism p , L s 、N p 、N s 、M wat , if otherwise the original secondary turns N p 、N s Add 1 successively and return to step A5.

[0079] The topology of underwater LCC-S type MC-WPT system is as follows Figure 6 As shown, U in It is a DC power supply, which is converted into high-frequency AC power u after passing through the full-bridge inverter circuit composed of switching devices S1-S4. AB The primary side is an LCC type compensation structure, including the compensation inductor L pr , parallel compensation capacitor C p1 And series compensation capacitor C p2 ; The secondary side is an S-type series compensation structure, including compensation capacitor C s ; L p , L s is the self-inductance of the transmitting coil and the receiving coil, M wat L in seawater environment p and L s The mutual inductance between them; D1-D4 are rectifier diodes (forming a full-bridge rectifier), C f is the filter capacitor, R L is the load resistance, U o is the output voltage.

[0080] The mutual inductance model of LCC-S type compensation structure is as follows Figure 7 As shown, R p1 is the internal resistance of the transmitting coil, R p2 is the equivalent resistance of eddy current loss at the transmitting end, R s1 is the internal resistance of the receiving coil, R s2 is the equivalent resistance of eddy current loss at the receiving end; the switching frequency is ω0, R eq is the equivalent resistance at the input end of the rectifier bridge,

[0081] It is known that in the underwater environment there are:

[0082] M wat =ρM air e -jα (4)

[0083] Among them, M air is the mutual inductance in air, ρ is the mutual inductance amplitude variation coefficient (approximately equal to 1), and α is the mutual inductance phase angle.

[0084] The internal resistance of capacitors and inductors is very small compared to their own impedance. To simplify the analysis, Figure 7 The equivalent internal resistance of the capacitor and inductor is neglected in the equivalent circuit shown. s With compensation capacitor C s When series resonance occurs, the equivalent impedance of the secondary side is:

[0085]

[0086] The secondary side reflection impedance is:

[0087]

[0088] Then the system input impedance Z in for:

[0089]

[0090] Substitute equations (5) and (6) into equation (7), and let the system input impedance Z in The imaginary part is 0, so:

[0091]

[0092] In formula (8), since the mutual inductance phase α is small, the resonance condition can be simplified to:

[0093]

[0094] Substituting formula (9) into formula (5), formula (6), and formula (7), we can obtain:

[0095]

[0096] Then the current in each branch of the system is:

[0097]

[0098] It is known that the voltage gain in seawater medium is:

[0099]

[0100] Due to R s1, R s2 Usually much smaller than the equivalent resistance R eq , so in the theoretical analysis process, it is usually ignored for the convenience of calculation. Then the voltage gain G in the seawater medium is V Can be simplified to:

[0101]

[0102] Input power P of underwater LCC-S topology network in , output power P out It can be expressed as:

[0103]

[0104]

[0105] Then the output efficiency of the underwater LCC-S topology network is:

[0106]

[0107] Therefore, in an underwater environment, if the eddy current loss equivalent resistance and the parasitic parameters of the system itself are not considered, the LCC-S type MC-WPT system can achieve constant voltage output. From equations (15) and (16), it can be seen that the change of mutual inductance will affect the output power and output efficiency. If the change of mutual inductance can be suppressed when the coupling mechanism is offset, the transmission performance of the system can be improved to a certain extent.

[0108] The following wireless charging system with an output power of not less than 3kW and a system efficiency of not less than 85% is taken as an example to verify the system and parameter design method proposed in the present invention. Taking into account the size and charging distance of commonly used underwater inspection robots, and based on engineering experience, the large circle radius of the transmitting coil and the receiving coil is designed to be 250mm, the spherical crown curvature is 40°, and the transmission distance is 150mm. In combination with the input and output voltages and the LCC-S topology, and considering the system's withstand voltage and current resistance, the transmitting coil uses Litz wire with a wire diameter of 6mm, and the receiving coil uses Litz wire with a wire diameter of 4mm. In the present invention, both the transmitting coil and the receiving coil are wound in a single layer, with a total of 20 turns. The coil structure is as follows Figure 8 As shown. Both the transmitting coil and the receiving coil are wound in DD type. The D-type coil on the left is wound clockwise, and the D-type coil on the right is wound counterclockwise, with 10 turns on the left and right sides. In order to further enhance the coupling ability of the system, a 5mm thick manganese-zinc ferrite is added to the outside of the coil as a magnetic core.

[0109] For the underwater MC-WPT system, it will be affected by surges from multiple directions of X, Y, and Z in the complex underwater environment, such as Fig. 9As shown. It can be seen that the receiving coil and the receiving end magnetic core are installed on the upper wall of the inclusive underwater inspection robot, the transmitting coil and the transmitting end magnetic core are installed in the horn-type docking station, the inclusive underwater inspection robot enters the docking station, and the transmitting end charges the inclusive underwater inspection robot. Due to the presence of the horn cage and the fixing device, the carrier will not have a large degree of shaking and offset, so the receiving end will not have a large angle offset state. According to engineering experience, the X-axis rotation offset angle is generally [-30°, 30°]. This example stipulates that [0°, 30°] is the offset in the positive direction, and [-30°, 0°] is the offset in the negative direction; the Y-axis rotation offset angle is generally [-10°, 10°], the Z-axis rotation offset angle is generally [-30°, 30°], the moving offset distance in the X direction is generally [-5cm, 5cm], and the moving offset distance in the Y direction is generally [-10cm, 10cm].

[0110] In response to surges from multiple angles, their impact on the coupling mechanism is simulated and the following offset analysis is performed. Due to the symmetry of the coupling mechanism, it is only necessary to analyze the offset in the positive direction. The situation in the negative direction is consistent with the result in the positive direction.

[0111] (1) X-axis rotation offset

[0112] For surge Fig. 9 The carrier causes a rotational offset along the X axis, simulating its influence on the coupling mechanism, and rotating the receiving end along the X axis, such as Fig.10 When the rotation angle is [0°, 30°] and the operating frequency is 150kHz, the mutual inductance changes as shown in Table 1. It can be seen that as the rotation angle increases, the mutual inductance value decreases and the mutual inductance change rate increases. When the rotation angle is 30°, the maximum mutual inductance change rate is 13.61%, and the mutual inductance phase changes slightly, always around -5.5°.

[0113] Table 1 X-axis rotation mutual inductance change

[0114]

[0115] (2) X-direction movement offset

[0116] For surge Fig. 9 The carrier in the middle causes the X-direction movement and deviation, and simulates its influence on the coupling mechanism, and moves the receiving end in the X-direction, such as Fig.11 When the offset distance is [0cm, 5cm] and the operating frequency is 150kHz, the mutual inductance changes as shown in Table 2. As the offset distance increases, the mutual inductance decreases and the mutual inductance change rate increases. When the displacement is 5cm, the maximum mutual inductance change rate is 14.92%, and the mutual inductance phase changes slightly. When the displacement is in the X direction, the mutual inductance decreases faster than when it moves in the Y direction.

[0117] Table 2 Mutual inductance change of X-direction movement offset

[0118]

[0119] (3) Y-direction movement offset

[0120] For surge Fig. 9 The carrier in the middle causes the Y-direction movement offset, simulates its influence on the coupling mechanism, and moves the receiving end in the Y direction, such as Fig.12 When the offset distance is [0cm, 10cm] and the operating frequency is 150kHz, the mutual inductance changes as shown in Table 3. As the offset distance increases, the mutual inductance decreases and the mutual inductance change rate increases. When the displacement is 10cm, the maximum mutual inductance change rate is 13.88%, and the mutual inductance phase remains basically unchanged.

[0121] Table 3 Mutual inductance variation in Y direction offset

[0122]

[0123] (4) Y-axis rotation offset

[0124] For surge Fig. 9 The carrier causes a rotational offset along the Y axis, simulating its influence on the coupling mechanism, and rotating the receiving end along the Y axis, such as Fig.13 When the rotation angle is [0°, 10°] and the operating frequency is 150kHz, the mutual inductance changes as shown in Table 4. As the rotation angle increases, the mutual inductance decreases and the mutual inductance change rate increases. When the rotation is 10°, the maximum mutual inductance change rate is 10.55%. When rotating along the Y axis, the mutual inductance decreases faster than when rotating along the X axis.

[0125] Table 4 Changes in mutual inductance of Y-axis rotation

[0126]

[0127] (5) Z-axis rotation offset

[0128] For surge Fig. 9 The carrier in the middle causes a rotational offset along the Z axis, simulating its influence on the coupling mechanism, and rotating the receiving end along the Z axis, such as Fig.14 When the rotation angle is [0°, 30°] and the operating frequency is 150kHz, the mutual inductance changes as shown in Table 5. As the rotation angle increases, the mutual inductance decreases and the mutual inductance change rate increases. When the rotation angle is 30°, the maximum mutual inductance change rate is 15.9%, and the mutual inductance phase changes slightly.

[0129] Table 5 Mutual inductance change of Z-axis rotation offset

[0130]

[0131] In order to further verify the anti-deviation performance of the spherical crown double D-type coupling mechanism, several common coupling mechanisms of the same size are constructed below, and the deviation simulation and analysis are performed on them.

[0132] Fig.15 The diagram is a schematic diagram of the rotation offset of the double U-shaped coupling mechanism. The size of the transmitting end and the receiving end is 500mm*500mm, and the transmission distance is 150mm. The transmitting coil of the double U-shaped coupling mechanism consists of a forward-wound transmitting coil and a reverse-wound transmitting coil. The forward-wound transmitting coil has 16 turns and a wire diameter of 6mm, and the reverse-wound transmitting coil has 7 turns and a wire diameter of 6mm; the receiving coil has 20 turns and a wire diameter of 4mm. When the receiving end is rotated and offset occurs, the rotation angle is [0°, 30°], and the operating frequency is 150kHz, the mutual inductance changes as shown in Table 6.

[0133] Table 6 Changes in mutual inductance of double U-shaped coupling mechanism rotation offset

[0134]

[0135] Fig.16 The figure is a schematic diagram of the rotation offset of the flat double D coupling mechanism. The size of the transmitting end and the receiving end is 500mm*500mm, and the transmission distance is 150mm. The transmitting coil is composed of DD coils. The D coil on the left is wound clockwise, with a wire diameter of 6mm and 13 turns. The D coil on the right is wound counterclockwise, with a wire diameter of 6mm and 13 turns. The receiving coil is also composed of DD coils. The D coil on the left is wound clockwise, with a wire diameter of 4mm and 13 turns. The D coil on the right is wound counterclockwise, with a wire diameter of 4mm and 13 turns. When the receiving end is rotated and offset occurs, the rotation angle is [0°, 30°], and the operating frequency is 150kHz, the mutual inductance changes as shown in Table 7.

[0136] Table 7 Changes in mutual inductance of double D-type flat plate rotation offset

[0137]

[0138] Fig.17 The diagram is a schematic diagram of the rotation offset of the spherical cap coupling mechanism. The radius of the spherical cap of the transmitter and the receiver is 250mm, and the transmission distance is 150mm. The transmitting coil consists of a forward-wound transmitting coil and a reverse-wound transmitting coil. The forward-wound transmitting coil has 16 turns and a wire diameter of 6mm, and the reverse-wound transmitting coil has 7 turns and a wire diameter of 6mm; the receiving coil has 20 turns and a wire diameter of 4mm. When the receiving end is rotated and offset occurs, the rotation angle is [0°, 30°], and the operating frequency is 150kHz, the mutual inductance changes as shown in Table 8.

[0139] Table 8 Changes in mutual inductance of spherical crown coupling mechanism with rotational offset

[0140]

[0141] Fig.18 The figure shows the comparison of the mutual inductance change rate of the spherical cap double D-type coil, double U-type coil, flat double D-type coil, and spherical cap coil under the same size and the same transmission distance when rotating and offsetting. Fig.18 It can be seen that within the rotation angle of [0°, 30°], the spherical cap double D-type coil has a smaller mutual inductance change rate than other coils, and its anti-rotational offset capability is greatly improved.

[0142] In addition, when the spherical cap double D-type coil is offset in the Y direction by [0cm, 10cm], the maximum mutual inductance change rate is 13.88%; when it is offset in the X direction by [0cm, 5cm], the maximum mutual inductance change rate is 14.92%; when the rotational offset occurs about the Y axis by [0°, 10°], the maximum mutual inductance change rate is 10.55%; when the rotational offset occurs about the Z axis by [0°, 30°], the maximum mutual inductance change rate is 14.8%; due to the symmetry of the coupling mechanism, the situation in the negative direction is consistent with the analysis of the positive side. In summary, the spherical cap double D-type coil has a certain degree of tolerance for the movement offset in the Y direction, the movement offset in the Z direction, the rotation offset on the Y axis, and the rotation offset on the X axis.

[0143] The present invention takes a wireless charging system with an output power of not less than 3kW and a system efficiency of not less than 85% as an example. According to the design requirements, the output voltage is 400V. Taking into account factors such as system withstand voltage, current resistance and efficiency, the input voltage is set to 250V, as shown in Table 9.

[0144] Table 9 System input and output parameters

[0145]

[0146] Combined with the results of COMSOL simulation software, the values ​​of mutual inductance, self-inductance and coil resistance are substituted into equations (1)-(8) to obtain the various parameters of the circuit. The design process is as follows: Fig.19 As shown, first determine the system power, efficiency, frequency, output voltage and load according to the design requirements and the power level of the underwater inspection robot, and determine the input voltage by comprehensively considering the system's withstand voltage and current levels. Combined with the results obtained by the COMSOL simulation software, the resonant parameters of the system are calculated according to the resonance conditions. If the output voltage and power of the system meet the requirements under these parameters, calculate the output efficiency of the system; if not, modify the compensation inductance according to the voltage gain formula so that the output voltage and power meet the requirements. After determining the above parameters, calculate the efficiency. If the requirements are met, output each system parameter; if not, adjust the input voltage, and repeat the above steps until the efficiency meets the requirements. Specifically includes the following steps:

[0147] B1. Determine the system output power P according to the design requirements and the rated power level of the underwater inspection robot. out , transmission efficiency η, operating frequency f, load resistance R L , output voltage U out ;

[0148] B2. Comprehensively consider the system voltage resistance, current resistance, power and efficiency factors to determine the system input DC voltage U in ;

[0149] B3, according to COMSOL software simulation, L p , L s 、M wat , R p , R s , R p is the internal resistance of the transmitting coil R p1 Equivalent resistance R to eddy current loss at the transmitting end p2 The sum, R s is the internal resistance of the receiving coil R s1 The equivalent resistance R of the eddy current loss at the receiving end s2 sum;

[0150] B4, by U out ≥(M wat(min) / L pr ) in The system resonance parameter L is obtained by the system resonance relationship pr , C p1 , C p2 , C s , M wat(min) It represents the minimum value of mutual inductance when the coupling mechanism is offset;

[0151] B5. Simulation calculation U out , P out Does it meet the requirements? If yes, go to the next step. If not, follow the U out ≥(M wat(min) / L pr ) in Modify L pr And recalculate U out , P out Until the requirements are met;

[0152] B6. Simulate and calculate whether η meets the requirements. If so, output the resonance parameters L of each system. pr , C p1 , C p2 , C s If not, adjust U in Return to step B4.

[0153] The obtained circuit simulation parameters are shown in Table 10.

[0154] Table 10 System simulation parameters

[0155]

[0156] The circuit simulation model is established using Simulink, which includes the main circuit model and drive circuit model of the LCC-S type MC-WPT system.

[0157] When there is no offset between the transmitting end and the receiving end, the inverter output voltage and current waveform of the system is as follows: Fig. 20 shown.

[0158] For the case of rotational offset of the X-axis, Y-axis, and Z-axis, select some mutual inductance values ​​within the specified offset range in Table 1, Table 4, and Table 5 and bring them into the simulation model in turn. The efficiency and power changes are as follows: Fig.21 As shown in (a) and (b), it can be seen from the figures that the output power is above 3kW and the output efficiency is above 85%.

[0159] For the case of displacement in the X and Y directions, a portion of the mutual inductance values ​​within the specified displacement range in Table 2 are selected and sequentially brought into the simulation model. The efficiency and power changes are as follows: Fig. 22 As shown in (a) and (b), it can be seen from the figures that the output power is above 3kW and the output efficiency is above 85%.

[0160] In summary, the present invention takes the wireless charging system with an output power of not less than 3kW and a system efficiency of not less than 85% as an example, and designs a spherical cap double D-type coil coupling mechanism and designs appropriate coupling mechanism parameters, and designs the primary and secondary side resonant network and designs appropriate resonant network parameters, so that the coupling mechanism has X-axis, Y-axis, Z-axis rotation offset and X-direction, Y-direction movement offset in three-dimensional space, and the mutual inductance changes less, and the system can still maintain an output efficiency of more than 85% and an output power of more than 3kW. The present invention uses COMSOL modeling to analyze that the mutual inductance change rate is small when there is an offset between the transmitting end and the receiving end in three-dimensional space. The present invention also verifies through MATLAB / Simulink simulation that the system can still maintain an output power of 3kW and a small power fluctuation when the mutual inductance changes, and the output efficiency is not less than 85%, thereby verifying the correctness and effectiveness of the system and parameter design method proposed by the present invention.

[0161] 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 equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A multi-angle anti-deviated underwater MC-WPT system based on a spherical cap double D-type coil, comprising a transmitting end and a receiving end, wherein the transmitting end comprises a DC power supply, a high-frequency inverter, a primary compensation network, and a transmitting coil connected in sequence, and the receiving end comprises a receiving coil, a secondary compensation network, a rectifier filter circuit, and a load connected in sequence, characterized in that: The transmitting coil adopts a spherical cap curvature of β The radius of the great circle is r dp , wire diameter is r p The number of turns is N p The first spherical cap double D-type coil is formed by connecting a symmetrical first D-type coil at the transmitting end and a second D-type coil at the transmitting end in opposite directions; the receiving coil adopts a spherical cap with a curvature of β The radius of the great circle is r ds , wire diameter is r s The number of turns is N s The second spherical cap double D-type coil is formed by connecting the symmetrical first D-type coil at the receiving end and the second D-type coil at the receiving end in opposite directions; the distance between the transmitting coil and the receiving coil, i.e. the wireless transmission distance, is d ; The transmitting end is also provided with a transmitting end magnetic core matching the shape of the transmitting coil, and the receiving end is also provided with a receiving end magnetic core matching the shape of the receiving coil. The thickness of the transmitting end magnetic core and the receiving end magnetic core are both H c ; The primary compensation network is an LCC type compensation structure, including a compensation inductor L pr , parallel compensation capacitor C p1 and series compensation capacitor C p2 ; The secondary side compensation network is an S-type series compensation structure, including a compensation capacitor C s ; The transmitting coil and the receiving coil are both wound in a single layer and meet the requirements r dp = r ds , N p = N s , r p > r s .

2. The multi-angle anti-deviated underwater MC-WPT system based on spherical cap double D-type coil according to claim 1 is characterized in that: The transmitting coil, the transmitting end magnetic core, the receiving coil, and the receiving end magnetic core form a coupling mechanism, and the parameters of the coupling mechanism are determined by the following steps: A1. Determined according to design requirements r dp , r ds 、β、d ; A2. Determine the wire diameter of the primary and secondary coils based on the system power and the current of the primary and secondary coils r p , r s ; A3. Determine the core thickness based on the self-inductance and mutual inductance requirements and engineering experience H c ; A4. Set the number of turns of the original and secondary coils N p = 1. N s = 1; A5. Simulate and calculate the self-inductance of the transmitting coil when the coupling mechanism is offset L p 、 Self-inductance of the receiving coil L s , the mutual inductance between the transmitting coil and the receiving coil in the underwater environment M wat ; A6. Determine mutual inductance M wat Whether the change meets the anti-drift requirement, if so, the various parameters of the coupling mechanism are output L p , L s , N p , N s , M wat , otherwise the original secondary turns N p , N s Add 1 successively and return to step A5.

3. The multi-angle anti-deviating underwater MC-WPT system based on spherical cap double D-type coil according to claim 2 is characterized in that: The parameters of the primary compensation network and the secondary compensation network are determined by the following steps: B1. Determine the system output power according to the design requirements and the rated power level of the underwater inspection robot P out 、 Transmission efficiency η、 Operating frequency f、 Load resistance R L 、 Output voltage U out ; B2. Comprehensively consider the system's withstand voltage, current resistance, power and efficiency to determine the system input DC voltage U in ; B3. According to COMSOL software simulation L p , L s , M wat , R p , R s , R p is the internal resistance of the transmitting coil R p1 Equivalent resistance to eddy current loss at the transmitting end R p2 the sum of R s is the internal resistance of the receiving coil R s1 Equivalent resistance to eddy current loss at the receiving end R s2 sum; B4. U out ≥ ( M wat(min) / L pr ) U in The system resonance parameters are obtained by the system resonance relationship L pr 、C p1 , C p2 、C s , M wat(min) Indicates the mutual inductance when the coupling mechanism is offset M wat The minimum value of B5. Simulation Calculation U out 、P out Does it meet the requirements? If yes, go to the next step. If not, follow the U out ≥ ( M wat(min) / L pr ) U in Revise L pr and recalculate U out 、P out Until the requirements are met; B6. Simulation Calculation η Whether it meets the requirements, if so, the resonance parameters of each system are output L pr 、C p1 , C p2 、C s If not, adjust U in Return to step B4.

4. The multi-angle anti-deviated underwater MC-WPT system based on spherical cap double D-type coil according to claim 3 is characterized in that: In step B4, the system resonance relationship is expressed as: ， Represents the operating angular frequency of the system.

5. The multi-angle anti-deviating underwater MC-WPT system based on spherical cap double D-type coil according to claim 1 is characterized in that: The receiving coil and the receiving end magnetic core are installed on the upper wall of the contained underwater inspection robot, and the transmitting coil and the transmitting end magnetic core are installed in a horn-type docking station. The contained underwater inspection robot enters the docking station, so that the receiving end enters the specified charging area, and the transmitting end charges the contained underwater inspection robot.

6. The multi-angle anti-deviated underwater MC-WPT system based on spherical cap double D-type coil according to claim 1 is characterized in that: The high frequency inverter adopts a full-bridge inverter circuit composed of switch devices S1, S2, S3, and S4.

7. The multi-angle anti-deviated underwater MC-WPT system based on spherical cap double D-type coil according to claim 1 is characterized by: The rectifier and filter circuit adopts a rectifier bridge and a filter capacitor C f The rectifier bridge adopts a full-bridge rectifier composed of diodes D1, D2, D3, and D4.

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