Magnetic coupler, wireless transmission system and parameter optimization and efficiency tracking method

Abstract

The invention provides a magnetic coupler, a wireless transmission system and a parameter optimization and efficiency tracking method, and relates to the technical field of wireless energy and data transmission. The magnetic coupler comprises a primary side and a secondary side, the secondary side comprises a cylindrical magnetic core and a secondary side coil, a plurality of hollow parts are arranged in the circumferential direction of the cylindrical magnetic core, and the secondary side coil is wound on the cylindrical magnetic core between the adjacent hollow parts; the primary side comprises a primary side coil and a plurality of I-shaped magnetic cores connected in sequence, the primary side coil comprises an outer magnetic field transmitting coil and an inner magnetic field transmitting coil, and each I-shaped magnetic core is arranged corresponding to the cylindrical magnetic core between the adjacent hollow parts. According to the invention, wireless energy transmission and wireless data transmission can be realized under an underwater working condition, and energy transmission can be realized by adopting a maximum transmission efficiency tracking control method. The system has the characteristics of light weight, strong offset fault tolerance, maximum energy transmission efficiency, full-duplex communication and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless energy and data transmission, and in particular to a magnetic coupler, a wireless transmission system, and a parameter optimization and efficiency tracking method. Background Art

[0002] With the increasing development of ocean resources, the endurance and efficiency of autonomous underwater vehicles (AUVs), a crucial underwater exploration tool, have become key factors limiting their widespread adoption. Traditional AUV refueling methods typically involve surface charging or underwater wet-swap charging. The former requires reliance on a mother ship or shore-based facilities, resulting in long operational interruptions, high sea-condition sensitivity, and strict requirements on the AUV's structure. The latter also presents complex operations, high precision requirements, a short service life, and issues with sealing and reliability. Traditional AUV data transmission methods often require the AUV to frequently return to the mother ship or shore-based facility for data downloads. This not only impacts the continuity of AUV operations but also increases the workload and operational difficulty of AUV recovery and redeployment, while also increasing wear and maintenance costs on mechanical equipment such as cranes and winches. Consequently, traditional AUV refueling and data transmission methods have severely hampered further improvements in AUV efficiency, safety, and application.

[0003] In recent years, wireless energy and data transmission technology has rapidly developed, providing new ideas and solutions for effectively addressing the aforementioned issues facing AUVs. Underwater wireless energy and data transmission systems that can perform both high-power energy transmission and high-speed data transmission within the same transmission link can effectively avoid the system complexity and high cost associated with separate couplers for energy and data transmission, thereby improving overall system performance and integration. Magnetic couplers are a key component of wireless energy / data transmission systems, and their design is crucial to improving overall system performance. Currently, most magnetic couplers used in electronic equipment, electric vehicles, and other fields are designed for air environments, which differ significantly from the underwater operating conditions of AUVs. Furthermore, the unique physical structure of AUVs requires a coupler structure and matching parameters tailored to their needs, requirements that conventional magnetic couplers cannot meet. Furthermore, AUV magnetic couplers should possess the following characteristics: 1) light weight to enhance the AUV's endurance; 2) strong anti-drift capability. Even if there is slight misalignment during docking between the AUV and the base station dock, a high coupling coefficient should be maintained between the primary and secondary sides of the coupler, thus reducing docking difficulties.

[0004] In practical applications of wireless energy transfer systems, the loose coupling characteristics of the system can easily lead to fluctuations in load characteristics during operation, causing the system to deviate from its maximum transmission efficiency operating point and resulting in a decrease in energy transfer performance. Therefore, studying how to maintain the system at maximum energy transfer efficiency based on the dynamic changes in load characteristics is crucial to improving the performance of wireless energy transfer systems. Summary of the Invention

[0005] The present invention aims to provide a magnetic coupler, wireless transmission system, and parameter optimization and efficiency tracking methods. The primary technical problem addressed is designing a system and corresponding magnetic coupler capable of wirelessly transmitting both energy and data for underwater AUVs. Energy transmission is achieved using a maximum efficiency tracking control method. The system boasts lightweight, high offset tolerance, maximum energy efficiency, and full-duplex communication.

[0006] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a magnetic coupler, comprising a primary side and a secondary side, wherein the secondary side is arranged inside the primary side, and a gap exists between the primary side and the secondary side; The secondary side includes a cylindrical magnetic core and a secondary side coil. The cylindrical magnetic core is provided with a plurality of hollow portions in the circumferential direction. The secondary side coil is wound on the cylindrical magnetic core between adjacent hollow portions. The primary side includes a primary side coil and a plurality of I-shaped magnetic cores connected in sequence. The primary side coil includes an external magnetic field transmitting coil and an internal magnetic field transmitting coil. Each I-shaped magnetic core is arranged corresponding to the cylindrical magnetic core between adjacent hollow portions. An upper boss and a lower boss are provided on the inner side surface of each I-shaped magnetic core along the axial direction of the cylindrical magnetic core. The external magnetic field transmitting coil is wound on the upper boss, and the internal magnetic field transmitting coil is wound on the lower boss. In each I-shaped magnetic core, the winding directions of the external magnetic field transmitting coil and the internal magnetic field transmitting coil are opposite. In two adjacent I-shaped magnetic cores, the external magnetic field transmitting coil of one I-shaped magnetic core is connected to the inner magnetic field transmitting coil of the other I-shaped magnetic core.

[0007] According to a magnetic coupler provided by the present invention, the cross section of the cylindrical magnetic core is circular or polygonal.

[0008] According to a magnetic coupler provided by the present invention, the magnetic coupler is applied to an autonomous underwater vehicle, the primary side is installed in the underwater base station dock, and the secondary side is embedded in the outer shell of the autonomous underwater vehicle. In a second aspect, the present invention provides a parameter optimization method for the magnetic coupler of the first aspect, comprising: Determine the structural parameters of the magnetic coupler that need to be optimized. These include the primary side parameters, the secondary side parameters, and the gap distance between the primary and secondary sides. The primary side parameters include the thickness of the I-shaped magnetic core, the radius of the primary coil, the number of coil turns, and the winding length. The secondary side parameters include the arc length of the cylindrical magnetic core between adjacent hollowed-out portions, the length of the cylindrical magnetic core, and the winding length of the secondary coil. Based on the magnetic coupling coefficient , taking the structural parameters as optimization variables and determining the objective function; Determine the constraints of the objective function based on actual needs; Genetic algorithm is used to determine the optimized structural parameters of the magnetic coupler.

[0009] According to a parameter optimization method for a magnetic coupler provided by the present invention, the objective function is:

[0010] in, is the magnetic induction intensity, and its expression is:

[0011] Where, is the relative magnetic permeability; is the integral range; is the magnetic permeability in vacuum; g is the gap distance between the primary side and the secondary side; R is the radius of the primary side coil; W1 is the thickness of the I-shaped magnetic core; L is the arc length of the cylindrical magnetic core between adjacent hollow parts; H1 is the length of the cylindrical magnetic core; I is the current of the primary side coil; h4 is the winding length of the primary side coil; is the winding length of the secondary side coil; N1 is the number of turns of the primary side coil.

[0012] In a third aspect, the present invention provides a wireless transmission system capable of wireless energy transmission and wireless data transmission under underwater working conditions; the wireless transmission system includes an energy transmission transmitting end, an energy transmission receiving end, a forward data transmission end, a reverse data transmission end, and the magnetic coupler of the first aspect; The energy transmission transmitting end includes a power supply, an inverter circuit, a primary compensation network, and a primary side of a magnetic coupler connected in sequence; the energy transmission receiving end includes a secondary side of a magnetic coupler, a secondary compensation network, a rectifier and filter circuit, a DC / DC converter circuit, and a battery load connected in sequence; The forward data transmission end includes a forward data carrier signal source, a primary side resonant capacitor Cp1, a forward communication transmitting coil, a forward communication receiving coil, a secondary side resonant capacitor Cs1, a first wave-blocking network and a sampling resistor Rr1; the reverse data transmission end includes a reverse data carrier signal source, a secondary side resonant capacitor Cs2, a reverse communication transmitting coil, a reverse communication receiving coil, a primary side resonant capacitor Cp2, a second wave-blocking network and a sampling resistor Rr2.

[0013] According to a wireless transmission system provided by the present invention, both wireless energy transmission and wireless data transmission are performed using magnetic resonance, wherein the excitation current frequency for wireless energy transmission is 20KHz~80KHz, and the wireless data transmission carrier frequency is 1MHz~10MHz.

[0014] According to a wireless transmission system provided by the present invention, multiple primary side coils on I-shaped magnetic cores and corresponding secondary side coils on cylindrical magnetic cores constitute multiple groups of transmitting coils and receiving coils, the forward communication transmitting coils and the forward communication receiving coils are collectively referred to as forward communication coils, and the reverse communication transmitting coils and the reverse communication receiving coils are collectively referred to as reverse communication coils; the forward communication coil is at least one group of the multiple groups of transmitting coils and receiving coils of the multiplexed magnetic coupler, and the reverse communication coil is at least one group of transmitting coils and receiving coils opposite to the multiplexed forward communication coil, and the forward communication coil and the reverse communication coil are 180 degrees apart in the circumferential direction; the carrier frequency used for forward data transmission and reverse data transmission is the same.

[0015] According to a wireless transmission system provided by the present invention, the DC / DC conversion circuit is a Zeta circuit, and the Zeta circuit includes a first capacitor, a second capacitor, a first inductor, a second inductor, a power switch tube and a rectifier diode; The power switch tube, the first capacitor, the second inductor, and the battery load are sequentially connected in series between the first output terminal and the second output terminal of the rectifier and filter circuit; One end of the first inductor is connected to the common connection end of the power switch tube and the first capacitor, and the other end is connected to the second output end of the rectifier and filter circuit; The cathode of the rectifier diode is connected to the common connection terminal of the first capacitor and the second inductor, and the anode is connected to the second output terminal of the rectifier filter circuit; One end of the second capacitor is connected to the common connection end of the second inductor and the battery load, and the other end is connected to the second output end of the rectifier and filter circuit.

[0016] In a fourth aspect, the present invention provides an efficiency tracking method for a wireless transmission system according to the third aspect, which implements maximum energy transmission efficiency tracking control by adjusting the duty cycle D of a power switch tube in a Zeta circuit; the duty cycle D is:

[0017] in, is the resistance of the battery load;

[0018] Indicates the system equivalent impedance when the wireless transmission system transmits at maximum energy transmission efficiency The value of the system equivalent impedance It is equivalent to the rectifier filter circuit, Zeta circuit and battery load; is the system energy transfer angular frequency; M is the mutual inductance between the primary and secondary sides; 、 are the internal resistances of the primary and secondary coils respectively.

[0019] Compared with the prior art, the present invention has at least the following technical effects: 1. In the wireless energy / data transmission system of the present invention, energy and data transmission share the same magnetic coupler and reuse the local coils of the overall magnetic coupler for data transmission. This avoids the system complexity and high cost associated with providing separate couplers for energy transmission and data transmission, thereby improving the overall performance and integration of the system.

[0020] 2. In the wireless energy / data transmission system of the present invention, the forward and reverse data transmission coils are spaced 180 degrees apart in the circumferential direction, so that two-way communication can use the same frequency, thereby saving bandwidth resources and achieving full-duplex same-frequency transmission.

[0021] 3. The magnetic core of the magnetic coupler of the present invention is designed as a hollow cylindrical structure on the secondary side, which improves the structural adaptability to the AUV shell; at the same time, it is beneficial to reduce the weight of the magnetic core to improve the endurance of the AUV.

[0022] 4. The magnetic coupler of the present invention adopts a circumferentially uniformly distributed design to improve the uniformity of the magnetic field and the offset fault tolerance characteristics, and constrains the magnetic field through the connection between the I-shaped magnetic cores, thereby enhancing the coupling performance while reducing the path of the magnetic field in the seawater and suppressing eddy current losses.

[0023] 5. The parameter optimization method of the magnetic coupler of the present invention performs parameter optimization through an optimization algorithm to obtain the best structural parameters of the magnetic coupler, thereby ensuring that the magnetic coupler has better working performance.

[0024] 6. The efficiency tracking method of the present invention adjusts the duty cycle in real time so that the system always maintains the maximum energy transmission efficiency under load changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] In the attached figure: Figure 1 This is a diagram of the wireless energy / data transmission system of the present invention; Figure 2 for Figure 1 Data transmission equivalent circuit diagram; Figure 3 for Figure 1 Energy transfer equivalent circuit diagram; Figure 4 This is a communication connection diagram of the magnetic coupler of the present invention; Figure 5 This is a simulated cloud diagram of the magnetic field of the magnetic coupler of the present invention; Figure 6 This is the overall structural diagram of the magnetic coupler of the present invention; Figure 7 This is a structural diagram of the secondary side of the magnetic coupler of the present invention; Figure 8 This is a structural diagram of the primary side of the magnetic coupler of the present invention; Figure 9 is the magnetic field direction diagram of the magnetic coupler of the present invention; Figure 10 This is a structural diagram of the secondary side of a magnetic coupler according to another embodiment of the present invention; Figure 11 This is a magnetic induction intensity analysis diagram of the present invention; Figure 12 It is the flow chart of the genetic algorithm of the present invention; Figure 13 This is a diagram of the iterative convergence process of the genetic algorithm of the present invention.

[0027] Reference numerals: 1. Secondary side; 2. Primary side; 3. Gap; 1_1. Cylindrical magnetic core; 1_2. Secondary side coil; 1_3. Hollow part; 2_1. I-shaped magnetic core; 2_2. External magnetic field transmitting coil; 2_3. Internal magnetic field transmitting coil. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0029] The following will describe some embodiments of the present invention in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0030] Aiming at the actual needs of AUVs, the present invention provides an underwater wireless energy / data transmission system and its magnetic coupler, and studies the corresponding energy transmission efficiency tracking and control method, which has important practical significance.

[0031] See also Figure 6 、 Figure 7 and Figure 8 , an embodiment of the present invention provides a magnetic coupler, Figure 6 : is a structural diagram of the magnetic coupler, which includes a primary side 2 and a secondary side 1. The secondary side 1 is arranged inside the primary side 2, and there is a gap 3 between the primary side 2 and the secondary side 1; The secondary side 1 includes a cylindrical magnetic core 1_1 and a secondary side coil 1_2. The cylindrical magnetic core 1_1 is provided with a plurality of hollow portions 1_3 in the circumferential direction. The secondary side coil 1_2 is wound around the cylindrical magnetic core 1_1 between adjacent hollow portions 1_3. The primary side 2 includes a primary side coil and a plurality of sequentially connected I-shaped magnetic cores 2_1. The primary side coil includes an external magnetic field transmitting coil 2_2 and an internal magnetic field transmitting coil 2_3. Each I-shaped magnetic core 2_1 is arranged corresponding to the cylindrical magnetic core 1_1 between adjacent hollow portions 1_3. The inner side surface of each I-shaped magnetic core 2_1 is provided with an upper boss and a lower boss along the axial direction of the cylindrical magnetic core 1_1. The external magnetic field transmitting coil 2_2 is wound around the upper boss, and the internal magnetic field transmitting coil 2_3 is wound around the lower boss. In each I-shaped magnetic core 2_1, the external magnetic field transmitting coil 2_2 and the internal magnetic field transmitting coil 2_3 are wound in opposite directions. In two adjacent I-shaped magnetic cores 2_1, the external magnetic field transmitting coil 2_2 of one I-shaped magnetic core 2_1 is connected to the internal magnetic field transmitting coil 2_3 of the other I-shaped magnetic core 2_1.

[0032] In some embodiments, as Figure 8 As shown, there are 8 I-shaped magnetic cores 2_1, which are evenly distributed in a regular octagonal pattern in the circumferential direction. The magnetic cores are used to guide the magnetic field, enhance the coupling degree, and improve the energy transmission efficiency.

[0033] The Litz wire is wound counterclockwise on the upper protrusion of the I-shaped magnetic core 2_1 to form the external magnetic field transmitting coil 2_2, and the end is wound in the opposite direction on the lower protrusion of the I-shaped magnetic core 2_1 to form the internal magnetic field transmitting coil 2_3. The winding direction is as follows: Figure 9 As shown by the green arrow, the end of the Litz wire is then wound around the upper protrusion of the next adjacent I-shaped magnetic core 2_1 according to the above steps until all the I-shaped magnetic cores 2_1 distributed circumferentially are wound. The direction of the magnetic field after winding must be that the magnetic field of the external magnetic field transmitting coil 2_2 is emitting the magnetic field outward, and the magnetic field of the internal magnetic field transmitting coil 2_3 is gathering the magnetic field inward. The two together form a closed magnetic circuit passing through the receiving coil. The direction of the magnetic circuit is as follows Figure 9 As shown by the red arrow, the receiving coil has a certain offset tolerance in the direction of the magnetic circuit.

[0034] Specifically, the cross section of the cylindrical magnetic core 1_1 is circular and is not completely hollow. The upper and lower ends thereof along the axial direction retain end core structures so as to have offset tolerance when rotating around the axis.

[0035] Litz wire is spirally wound around the cylindrical magnetic core 1_1 (hereinafter referred to as the arc-shaped curved core) between adjacent hollow sections 1_1. The end of the Litz wire is then wound around another adjacent arc-shaped curved core until all the arc-shaped curved cores are wound around, forming the secondary coil 1_2. The winding direction must ensure that the magnetic field direction of the coil on each arc-shaped curved core is consistent. The specific number of turns can be determined based on factors such as the power of the specific charging system.

[0036] Specifically, in the magnetic coupler, multiple I-shaped magnetic cores 2_1 on the primary side are connected in sequence along the circumference. This design aims to effectively confine the magnetic field inside the magnetic coupler, enhance coupling performance, reduce the path of the magnetic field in the seawater, and suppress eddy current losses in the seawater.

[0037] In other embodiments, the cross section of the cylindrical magnetic core 1_1 may also be polygonal, such as Figure 10 shown.

[0038] Specifically, the magnetic coupler is applied to an AUV. When in use, the primary side 2 is installed in an underwater base station dock, and the secondary side 1 is embedded in the outer shell of the AUV.

[0039] There is a certain gap 3 between the primary side 2 and the secondary side 1. The gap 3 is determined by the wall thickness of the AUV. The size of the gap 3 can be determined according to the specific AUV model.

[0040] The coupling degree can be adjusted to meet the requirements of gaps of different sizes by designing the external magnetic field transmitting coil 2_2 and the internal magnetic field transmitting coil 2_3 with different diameters.

[0041] To ensure that the magnetic coupler has good working performance, the present invention provides a parameter optimization method for the magnetic coupler of the aforementioned embodiment, which is performed according to the following steps: S1: Determine the structural parameters of the magnetic coupler that need to be optimized. The structural parameters include primary side parameters, secondary side parameters, and the gap distance between primary side 2 and secondary side 1. The primary side parameters include the thickness of the I-shaped magnetic core 2_1 and the radius, number of coil turns, and winding length of the primary side coil. The secondary side parameters include the arc length of the cylindrical magnetic core 1_1 between adjacent hollow portions 1_3, the length of the cylindrical magnetic core 1_1, and the number of coil turns and winding length of the secondary side coil 1_2. S2: Based on the magnetic coupling coefficient k, the structural parameters are used as optimization variables to determine the objective function. In order to improve the underwater coupling performance between the primary and secondary sides, according to the calculation formula of the magnetic coupling coefficient , taking the optimization parameters of S1 as variables, analyze the relevant factors affecting the mutual inductance coefficient M and self-inductance coefficients L1 and L2 of the coils on both sides of the magnetic coupler, and determine the optimization objective function; S3: Determine the constraints of the objective function based on actual needs.

[0042] S4: Using genetic algorithm, determine the optimized structural parameters of the magnetic coupler.

[0043] Analyze the magnetic coupler and establish Figure 11 The analysis model is shown below; where R is the radius of the primary coil; g is the gap between the primary side 2 and the secondary side 1; W1 is the thickness of the I-shaped magnetic core 2_1; H1 is the length of the cylindrical magnetic core 1_1; and L is the arc length of the cylindrical magnetic core 1_1 between adjacent hollow portions 1_3. The specific analysis is as follows: According to the Biot-Savart law, the magnetic induction intensity of a circular coil at any point in space is: (1) Where, is the magnetic permeability in vacuum; I is the current intensity; r is the differential current element The distance to that point in space; Since the magnetic flux is the quantity that passes vertically through the receiving end plane, the magnetic induction intensity in the x direction is taken as ,Depend on Figure 11 It can be seen that: (2) because , , , so the magnetic induction intensity in the x direction at a point in space is: (3) If the curvature of the cylindrical magnetic core 1_1 between adjacent hollow portions 1_3 serving as the receiving magnetic core is small, it can be equivalent to a rectangular parallelepiped. The magnetic induction intensity of the rectangular parallelepiped is: (4) in, ; The mutual inductance between the coils is: (5) Since the primary side is in the shape of a solenoid, the self-inductance is: (6) Wherein, N1 is the number of turns of the primary coil; h4 is the winding length of the primary coil; is the relative magnetic permeability.

[0044] The secondary side is equivalent to a rectangular solenoid coil, and the self-inductance is: (7) Where N2 is the number of turns of the secondary coil, is the winding length of the secondary side coil.

[0045] Combining equations (5), (6) and (7), we can get the coupling coefficient formula, that is, the objective function is: (8) In practice, the radius R of the primary coil is less than half the arc length L to reduce the large amount of magnetic flux leakage that cannot reach the secondary side. The thickness W1 of the I-shaped magnetic core at the receiving end should be less than 15mm to reduce the burden on the AUV. The length H1 of the cylindrical magnetic core should not exceed 2 / 3 of the length H3 of the corresponding cabin section on the AUV. When eight groups are arranged in a circular direction, the sector angle between each group is 45°. To avoid interference between coils between arcs and increase the hollow area, each group occupies 1 / 10 of the arc, and the arc length L is less than 10% of R1 (AUV radius). That is: (9) Based on the same inventive concept, another embodiment of the present invention provides a wireless transmission system, comprising an energy transmission transmitter, an energy transmission receiver, a forward data transmission terminal, a reverse data transmission terminal, and the magnetic coupler of the aforementioned embodiment; The energy transmission transmitter includes a power supply E connected in sequence dc , inverter circuit, primary compensation network and magnetic coupler primary side L p The energy transmission receiving end includes a magnetic coupler secondary side L connected in sequence s , secondary side compensation network, rectifier filter circuit, DC / DC conversion circuit and battery load R; The forward data transmission end includes a forward data carrier signal source Usig1, a primary side resonant capacitor Cp1, a forward communication transmitting coil Lp1, a forward communication receiving coil Ls1, a secondary side resonant capacitor Cs1, a first wave-blocking network and a sampling resistor Rr1; the reverse data transmission end includes a reverse data carrier signal source Usig2, a secondary side resonant capacitor Cs2, a reverse communication transmitting coil Ls2, a reverse communication receiving coil Lp2, a primary side resonant capacitor Cp2, a second wave-blocking network and a sampling resistor Rr2.

[0046] In some embodiments, the inverter circuit is a full-bridge inverter bridge composed of four MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) Q1-Q4. The primary compensation network includes a primary resonant inductor L fp , capacitor C fp , capacitor C p The secondary side compensation network includes the secondary side resonant inductor L fs , capacitor C fs , capacitor C s The rectifier and filter circuit consists of a full-bridge rectifier (composed of four diodes D1-D4) and filter capacitor C1. The DC / DC converter circuit is a Zeta circuit. The first wave-blocking network includes inductor Lr1 and capacitor Cr1 in parallel. The second wave-blocking network includes inductor Lr2 and capacitor Cr2 in parallel.

[0047] It should be noted that the basic energy transmission process of the wireless transmission system is as follows: at the transmitting end, the DC voltage E dc The full-bridge inverter bridge converts the high-frequency square wave signal into the primary compensation network, and the primary side L of the magnetic coupler p Generates magnetic field and magnetic coupler secondary side L s Couple and transfer energy to the secondary side L of the magnetic coupler sAt the receiving end, the reactive power is further compensated by the secondary side compensation network, and finally passes through the full-bridge rectifier bridge, filter capacitor C1 and Zeta circuit to provide power to the battery load R, thereby realizing wireless energy transmission. The forward data transmission process is as follows: the serial port USART1 and the signal generator generate a modulation signal (signal source) Usig1 through an analog switch, which resonates with the capacitor Cp1 and the coil Lp1. The coil Lp1 and the coil Ls1 convert the magnetic field energy into electrical energy. The coil Ls1 resonates with the first wave-blocking network composed of the capacitor Cs1, the inductor Lr1 and the capacitor Cr1, and transmits the data to the sampling resistor Rr1. After demodulation, it is sent to the serial port USART2 to obtain the data; the reverse data transmission process is as follows: the serial port USART2 and the signal generator generate a modulation signal (signal source) Usig2 through an analog switch, which resonates with the capacitor Cs2 and the coil Ls2. The coil Lp2 and the coil Ls2 convert the magnetic field energy into electrical energy. The coil Lp2 resonates with the second wave-blocking network composed of the capacitor Cp2, the inductor Lr2 and the capacitor Cr2, and transmits the data to the sampling resistor Rr2. After demodulation, it is sent to the serial port USART1 to obtain the data.

[0048] The crosstalk analysis is now carried out.

[0049] Analysis of the interference of data transmission on energy transmission. When transmitting data in the forward direction, the energy circuit is equivalent to the following Figure 2 The energy resistance Z shown T3 , Z R3 , there is a relationship: (10) System energy transfer angular frequency Much smaller than the forward data carrier angular frequency , and from formula (10), we can know that at the forward data carrier angular frequency It presents high impedance, so the energy transfer loop can be regarded as an open circuit, and the same applies to reverse transmission.

[0050] Analysis of interference of energy transmission on data transmission. Figure 3 for Figure 1 Equivalent energy transmission diagram, the data transmission channel is respectively connected to the coil L of the magnetic coupler p1 、L s1 、L p2 、L s2 In parallel, the impedance of each channel is Z T1 , Z R1 , Z T2 , Z R2 for: (11) Where R S1 、R S2 、R p1 、Rp2 Coil L p1 、L s1 、L p2 、L s2 internal resistance; is the system energy transfer angular frequency. Much smaller than the forward data carrier angular frequency and reverse data carrier angular frequency , in the system energy transfer angular frequency Each data transmission channel presents high impedance, the influence of the energy transmission channel on data transmission can be ignored, and the data transmission channel is regarded as an open circuit.

[0051] It should be noted that the wireless transmission system of the present invention can perform wireless energy transmission and data transmission underwater, and the wireless energy transmission and data transmission share the same magnetic coupler.

[0052] The data transmission coil is a local winding selected based on the energy transmission of the whole coil. That is, the data transmission transmitting and receiving coils both lead out two wires to connect to the data transmission transmitting circuit and receiving circuit respectively. The connection is as follows Figure 4 To address crosstalk between energy and data transmission, both are performed using magnetic resonance. The excitation current frequency for energy transmission is 20 kHz to 80 kHz, while the data transmission carrier frequency is 1 MHz to 10 MHz. This effectively avoids crosstalk and ensures stable and reliable energy and data transmission.

[0053] It should be noted that in the magnetic coupler, since each I-shaped magnetic core corresponds to the cylindrical magnetic core arrangement between adjacent hollow portions, the primary coils on the multiple I-shaped magnetic cores and the secondary coils on the corresponding cylindrical magnetic cores between adjacent hollow portions constitute multiple sets of transmitting coils and receiving coils. The forward communication transmitting coil and the forward communication receiving coil (collectively referred to as the forward communication coil) are any one set of the multiple sets of transmitting coils and receiving coils of the multiplexed magnetic coupler; the reverse communication transmitting coil and the reverse communication receiving coil (collectively referred to as the reverse communication coil) are a set of transmitting coils and receiving coils opposite to the multiplexed forward communication coil, such as Figure 4 As shown in the light blue part in the middle. Of course, the forward communication coil and the reverse communication coil can reuse one or more sets of multiple transmitting coils and receiving coils of the magnetic coupler. Reusing multiple sets enables better offset characteristics for communication, and can be selected according to the required offset situation.

[0054] Figure 5This is a cloud diagram of the magnetic field simulation analysis of the magnetic coupler. The magnetic field is effectively confined within the magnetic core. The magnetic fields of each coil group on the primary side precisely correspond to those of the corresponding coil group on the secondary side, and the magnetic induction intensity within the secondary side approaches zero. The forward and reverse data transmission coils are spaced 180° apart circumferentially, and the communication power is low, making bidirectional crosstalk negligible. Therefore, forward and reverse communication can use the same frequency band or independent frequency bands, depending on the AUV diameter and transmission rate requirements. Larger AUVs can communicate on the same frequency, while smaller AUVs can operate on the same or different frequencies due to the potential for low crosstalk.

[0055] Specifically, the Zeta circuit includes a first capacitor C2, a second capacitor C3, a first inductor L1, a second inductor L2, a power switch Q5, and a rectifier diode D5. The power switch Q5, first capacitor C2, second inductor L2, and load R are connected in series between the first and second output terminals of the rectifier and filter circuit (filter capacitor C1). The control terminal of the power switch Q5 is connected to a controller. One end of the first inductor L1 is connected to the common connection terminal of the power switch Q5 and the first capacitor C2, and the other end is connected to the second output terminal of the rectifier and filter circuit (filter capacitor C1). The cathode of the rectifier diode D5 is connected to the common connection terminal of the first capacitor C2 and the second inductor L2, and the anode is connected to the second output terminal of the rectifier and filter circuit (filter capacitor C1). One end of the second capacitor C3 is connected to the common connection terminal of the second inductor L2 and the load R, and the other end is connected to the second output terminal of the rectifier and filter circuit (filter capacitor C1).

[0056] When the power switch Q5 is turned on, the input voltage charges the first inductor L1. At the same time, the first capacitor C2 releases the energy charged when the power switch Q5 is turned off in the previous cycle to charge the second inductor L2. At this time, due to the high potential above the rectifier diode D5, the rectifier diode D5 is turned off, forming two loops: the input filter capacitor C1 Power switch Q5 First inductor L1, input filter capacitor C1 Power switch Q5 First capacitor C2 The second inductor L2 Load R; When power switch Q5 is turned off, the first inductor L1 generates an induced electromotive force (EMF) with a positive bottom and a negative top. This energizes the first capacitor C2 through the rectifier diode D5. The current loop is: first inductor L1 → rectifier diode D5 → first capacitor C2. Furthermore, the second inductor L2 also generates an induced electromotive force, which powers the load R. The current loop is: second inductor L2 → load R → rectifier diode D5.

[0057] For the Zeta circuit in continuous current mode (CCM), let the on-time of the power switch Q5 be D and the off-time be 1-D. D is also the duty cycle of the PWM control signal that controls the gate (control terminal) of the power switch Q5. Then, for the current of the inductor L1, we have: (12) Among them, V c1 is the voltage across the filter capacitor C1, V c2 is the voltage across the first capacitor C2.

[0058] In steady state, the total energy of inductor L1 in one cycle is 0, that is, , then: (13) The current of inductor L2 is: (14) Among them, V o is the output voltage.

[0059] In steady state, the total energy of the second inductor L2 in one cycle is 0, that is, , then: (15) Combining (13) and (15), we get: (16) Ignoring the loss of the Zeta circuit, according to the law of conservation of energy, the input impedance R of the Zeta circuit is Zeta and output impedance The relationship can be expressed as: (17) Figure 3 for Figure 1 The equivalent circuit diagram of the LCC-LCC type wireless energy / data transmission system is shown in FIG. AB is the equivalent high-frequency voltage source output by the inverter circuit; R p 、R s They are respectively the primary side L of the magnetic coupler p and the secondary side of the magnetic coupler L s The internal resistance of the coil; M is the mutual inductance between the primary and secondary sides of the magnetic coupler; I p , I s are the currents of the primary and secondary resonant circuits respectively; I fp , I fs are the total current of the primary and secondary sides respectively; R L is the equivalent value of the rectifier filter circuit, Zeta circuit and battery load, where: (18) From the above formulas (10) and (11), we can see that the data channel can be regarded as an open circuit when analyzing energy transmission. Figure 3 The LCC-LCC compensation network structure shown has the following relationship: (19) Where: Represents the system energy transfer angular frequency.

[0060] When the system is in resonance, that is: (20) Combining (19), the current can be obtained as: (twenty one) for Figure 3 The transmission efficiency of the underwater wireless power transmission system shown is: (twenty two) Apply formula (22) to R L Take the derivative and set it to 0, then take the second derivative to determine if it is less than 0, that is: (twenty three) Thus, the equivalent value under maximum transmission efficiency is obtained: (twenty four) From formula (17) and formula (18), we can get: (25) From formula (25), it can be seen that the duty cycle D can be adjusted so that the system equivalent impedance At the optimal value, combining equations (24) and (25) we can get the duty cycle at the maximum transmission efficiency: (26) The gate of the power switch tube Q5 can be controlled in real time through the duty cycle D according to formula (26), so that the system is in the maximum efficiency transmission.

[0061] Applying the above analysis to carry out specific operations, the genetic algorithm uses k as the fitness function and formula (9) as the constraint condition for optimization. The population size is set to 360, the termination evolution generation is 300, the crossover probability is 0.8, and the mutation probability is 0.01. The process is as follows: Figure 12 As shown; like Figure 13As shown in the figure, after 360 iterations, k converged to 0.57. The magnetic coupler parameters are as follows: the gap is 15 mm, the primary and secondary sides are divided into 8 groups with uniform circumferential arrangement, the diameter of the cylindrical core 1_1 is 270 mm, the thickness is 10 mm, the length is 200 mm, and the winding length is 40 mm. Each curved surface is wound with 6 turns, and a 21° hollowing is performed every 24° along the circumferential direction, for a total of eight turns on the entire circumference; the diameter of the internal and external magnetic field emitting cores (lower and upper protrusions) on the primary side is 50 mm, the winding length of the primary side coil is 20 mm, and each is wound with 4 turns.

[0062] Using Maxwell to simulate and analyze the magnetic coupler, the receiving end was moved along the axis from -20mm to 20mm. The self-inductance, mutual inductance, and coupling coefficient were recorded and collected, as shown in Table 1. The table shows that the coupling coefficient changes very little with an axial offset of 20mm. The secondary side was rotated every 22.5° for a total of 360°, and the change in the coupling coefficient was observed. As shown in Table 2, the change was very small. Radial offset was also observed, as shown in Table 3. The offset actually increased the coupling coefficient. By varying the gap (wall thickness) by 3 and keeping other parameters constant, different coil diameters were designed to stabilize the desired coupling coefficient, as shown in Table 4. This demonstrates that the desired coupling parameters can be achieved by designing different diameters.

[0063]

[0064]

[0065]

[0066]

[0067] To verify the maximum efficiency tracking method proposed in the present invention, the gap of the magnetic coupler is selected as 15 mm and the coupling coefficient is selected as 0.57. A power electronics simulation is built in Simulink of Matlab to determine the power transmission parameters of the LCC-LCC wireless transmission system as shown in Table 5, and the parameters of the Zeta circuit are shown in Table 6.

[0068]

[0069]

[0070] According to Equation (24), the optimal load for the system is 7Ω. The system energy transfer efficiency was tested before and after the Zeta circuit was added under different loads. According to Equation (26), the duty cycle value when the Zeta circuit tracks the maximum efficiency can be obtained. Multiple sets of data are obtained, as shown in Table 7. Without the Zeta circuit, the system efficiency is 81.05% when the load is at the optimal 7Ω load. When the load deviates from the optimal load, the system efficiency decreases. After the Zeta circuit is added, the Zeta circuit's duty cycle can be adjusted to achieve optimal load matching within any load range, allowing the system to maintain energy transfer near the maximum efficiency point.

[0071]

[0072] In summary, the present invention provides a wireless energy / data transmission system suitable for underwater operation, its magnetic coupler, and an energy transmission efficiency tracking and control method. The system analyzes the impact of data transmission on energy transmission and vice versa, and constructs an impedance model for the wireless energy / data transmission system. By constructing an objective function for the coupling coefficient, a genetic algorithm is used to optimize parameters such as the magnetic coupler core and coil. A Zeta circuit is used as the post-stage DC / DC converter circuit for impedance matching. A controller adjusts the duty cycle of the power switch Q5 in the Zeta circuit to achieve maximum efficiency tracking and control.

[0073] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the embodiments disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and variations can be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A magnetic coupler, characterized in that: It includes a primary side and a secondary side, wherein the secondary side is arranged inside the primary side, and there is a gap between the primary side and the secondary side; The secondary side includes a cylindrical magnetic core and a secondary side coil, wherein the cylindrical magnetic core is provided with a plurality of hollow portions in the circumferential direction, and the secondary side coil is wound on the cylindrical magnetic core between adjacent hollow portions; The primary side includes a primary side coil and a plurality of I-shaped magnetic cores connected in sequence. The primary side coil includes an external magnetic field transmitting coil and an internal magnetic field transmitting coil. Each I-shaped magnetic core is arranged corresponding to the cylindrical magnetic core between adjacent hollow portions. The inner side surface of each I-shaped magnetic core is provided with an upper boss and a lower boss along the axial direction of the cylindrical magnetic core. The external magnetic field transmitting coil is wound on the upper boss, and the internal magnetic field transmitting coil is wound on the lower boss. In each I-shaped magnetic core, the winding direction of the external magnetic field transmitting coil is opposite to that of the internal magnetic field transmitting coil. In two adjacent I-shaped magnetic cores, the external magnetic field transmitting coil of one I-shaped magnetic core is connected to the internal magnetic field transmitting coil of the other I-shaped magnetic core.

2. The magnetic coupler according to claim 1, wherein: The cross section of the cylindrical magnetic core is circular or polygonal.

3. The magnetic coupler according to claim 1, wherein: The magnetic coupler is applied to an autonomous underwater vehicle, the primary side is installed in an underwater base station dock, and the secondary side is embedded in an outer shell of the autonomous underwater vehicle.

4. A parameter optimization method for a magnetic coupler according to any one of claims 1 to 3, characterized in that: include: Determining structural parameters of the magnetic coupler that need to be optimized, the structural parameters including primary side parameters, secondary side parameters, and a gap distance between the primary side and the secondary side; the primary side parameters include the thickness of the I-shaped magnetic core and the radius, number of coil turns, and winding length of the primary side coil; the secondary side parameters include the arc length of the cylindrical magnetic core between adjacent hollow portions, the length of the cylindrical magnetic core, and the winding length of the secondary side coil; Based on the magnetic coupling coefficient , taking the structural parameters as optimization variables and determining the objective function; Determine the constraints of the objective function according to actual needs; Genetic algorithm is used to determine the optimized structural parameters of the magnetic coupler.

5. The parameter optimization method of the magnetic coupler according to claim 4, characterized in that: The objective function is: in, is the magnetic induction intensity, and its expression is: Where, is the relative magnetic permeability; is the integral range; is the magnetic permeability in vacuum; g is the gap distance between the primary side and the secondary side; R is the radius of the primary side coil; W1 is the thickness of the I-shaped magnetic core; L is the arc length of the cylindrical magnetic core between adjacent hollow parts; H1 is the length of the cylindrical magnetic core; I is the current of the primary side coil; h4 is the winding length of the primary side coil; is the winding length of the secondary side coil; N1 is the number of turns of the primary side coil.

6. A wireless transmission system, characterized in that: The wireless transmission system can perform wireless energy transmission and wireless data transmission under underwater working conditions; the wireless transmission system includes an energy transmission transmitting end, an energy transmission receiving end, a forward data transmission end, a reverse data transmission end, and the magnetic coupler according to any one of claims 1 to 3; The energy transmission transmitting end includes a power supply, an inverter circuit, a primary compensation network and a primary side of a magnetic coupler connected in sequence; the energy transmission receiving end includes a secondary side of a magnetic coupler, a secondary compensation network, a rectifier and filter circuit, a DC / DC converter circuit and a battery load connected in sequence; The forward data transmission end includes a forward data carrier signal source, a primary side resonant capacitor Cp1, a forward communication transmitting coil, a forward communication receiving coil, a secondary side resonant capacitor Cs1, a first wave blocking network and a sampling resistor Rr1; The reverse data transmission end includes a reverse data carrier signal source, a secondary side resonant capacitor Cs2, a reverse communication transmitting coil, a reverse communication receiving coil, a primary side resonant capacitor Cp2, a second wave blocking network and a sampling resistor Rr2.

7. The wireless transmission system according to claim 6, wherein: The wireless energy transmission and wireless data transmission are both performed using magnetic resonance, wherein the excitation current frequency for the wireless energy transmission is 20KHz~80KHz, and the wireless data transmission carrier frequency is 1MHz~10MHz.

8. The wireless transmission system according to claim 6, wherein: The primary side coils on multiple I-shaped magnetic cores and the secondary side coils on the corresponding cylindrical magnetic cores constitute multiple groups of transmitting coils and receiving coils. The forward communication transmitting coils and the forward communication receiving coils are collectively referred to as forward communication coils, and the reverse communication transmitting coils and the reverse communication receiving coils are collectively referred to as reverse communication coils. The forward communication coil is at least one group of the multiple groups of transmitting coils and receiving coils of the multiplexed magnetic coupler, and the reverse communication coil is at least one group of transmitting coils and receiving coils opposite to the multiplexed forward communication coil. The forward communication coil and the reverse communication coil are 180 degrees apart in the circumferential direction. The carrier frequency used for the forward data transmission and the reverse data transmission is the same.

9. The wireless transmission system according to claim 6, wherein: The DC / DC conversion circuit is a Zeta circuit, which includes a first capacitor, a second capacitor, a first inductor, a second inductor, a power switch tube and a rectifier diode; The power switch tube, the first capacitor, the second inductor, and the battery load are sequentially connected in series between the first output terminal and the second output terminal of the rectifier and filter circuit; One end of the first inductor is connected to the common connection end of the power switch tube and the first capacitor, and the other end is connected to the second output end of the rectifier and filter circuit; The cathode of the rectifier diode is connected to the common connection terminal of the first capacitor and the second inductor, and the anode is connected to the second output terminal of the rectifier filter circuit; One end of the second capacitor is connected to the common connection end of the second inductor and the battery load, and the other end is connected to the second output end of the rectifier and filter circuit.

10. An efficiency tracking method for a wireless transmission system according to claim 9, characterized in that: The maximum energy transmission efficiency tracking control is achieved by adjusting the duty cycle D of the power switch tube in the Zeta circuit; the duty cycle D is: in, is the resistance of the battery load; Indicates the system equivalent impedance when the wireless transmission system transmits at maximum energy transmission efficiency The value of the system equivalent impedance It is equivalent to the rectifier filter circuit, the Zeta circuit and the battery load; is the system energy transfer angular frequency; M is the mutual inductance between the primary and secondary sides; 、 are the internal resistances of the primary coil and the secondary coil respectively.

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