A coupler offset monitoring and control method suitable for underwater wireless charging

Abstract

The present invention provides a coupler offset monitoring and control method suitable for underwater wireless charging, comprising: designing a relay coil structure based on the coupler, determining that the relay coil current can represent the change in the mutual inductance coefficient between the relay coil and the secondary coil; utilizing a BP neural network to obtain a solution matrix for the coupler offset and the relay coil current; and during charging, determining the offset direction and offset of the primary and secondary coils based on the collected current values ​​through the solution matrix, and controlling the control mechanism of the primary coil to align it with the secondary coil, thereby ensuring that the coupler maintains precise coupling. The relay coil in the present invention can enhance the coupling coefficient, expand the electromagnetic field transmission distance, and achieve passive anti-offset. It can also monitor the current parameters in the arrayed relay coil, implement offset and deflection detection through coil array current sampling, and perform active anti-offset, thereby improving the efficiency and stability of underwater wireless charging.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater wireless charging, and in particular relates to a coupler offset monitoring and control method suitable for underwater wireless charging. Background Art

[0002] Underwater vehicles (UVs) are essential tools for underwater exploration and exploration, and are currently used in numerous industries. However, their limited space limits the amount of power they can carry, making continuous underwater operations a bottleneck for their development. Underwater wireless charging technology, which transfers energy through the electromagnetic field between coupled coils, allows for rapid underwater energy recharge in a compact space, significantly enhancing the ability of underwater vehicles to operate continuously.

[0003] However, due to the complexity of the underwater environment, there are the following problems with underwater docking and charging of aircraft: First, the underwater docking accuracy with the charging platform is low. Due to the influence of sea water fluctuations and changes in additional mass, the aircraft will have problems such as "misalignment" and "unstable parking"; Second, after docking, the coupler will be offset by the impact of ocean currents. The offset will directly affect the coupling coefficient of the coupler, thereby reducing the efficiency and stability of wireless charging, and even affecting charging safety.

[0004] The underwater vehicle wireless charging coupler offset detection and control technology can monitor the offset degree between the charging couplers in real time, promptly correct the relative motion between the vehicle and the charging base station, and maintain precise coupling even in complex underwater environments, thereby avoiding the decrease in energy transmission efficiency or charging interruption caused by coupler offset.

[0005] At present, the commonly used offset control method for underwater wireless charging couplers is to adopt an asymmetric design with a large transmitter and a small receiver. However, this method only has passive anti-offset characteristics and cannot detect the offset for active control. In addition, there are many offset detection methods in the field of wireless charging of electric vehicles, which simplify the coupler offset to a translation in the same plane (for example, the Chinese patent with application number 202180098719.1 and invention name "Wireless Charging Pad, Offset Detection Method of Wireless Charging Pad and Wireless Charging System" uses a metal relay coil matrix to detect the metal chassis of the vehicle to achieve wireless charging coupler offset detection and control), or simplify it to a three-degree-of-freedom translation. However, these methods ignore the coupler deflection problem that often occurs in underwater docking charging. Therefore, they cannot distinguish between coupler translation and deflection, and cannot detect coupler deflection. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems in the prior art of the inability to achieve active anti-drift control and coupler deflection detection for the offset control of underwater wireless charging couplers. A coupler offset monitoring and control method suitable for underwater wireless charging is provided. By adding a relay coil array in the middle of the wireless charging coupler and sampling it, the coupling coefficient can be enhanced, the electromagnetic field transmission distance can be extended to achieve passive anti-drift, and the current parameters in the arrayed relay coil can be used as the monitoring object. The offset and deflection detection can be achieved through coil array current sampling, thereby performing active anti-drift.

[0007] Furthermore, the applicant discovered that, unlike the offset during docking, the offset that occurs during docking and charging is characterized by smaller magnitude, slower speed, and uncertain direction. During simulation and experimental design, the applicant discovered that offset during charging is difficult to determine with a single test, requiring rapid, multiple tests and rapid identification to determine the offset. To address this new issue, the applicant considered using a convolutional neural network to obtain a solution matrix for the offset and current. Specifically, after detecting the relay coil array current parameters, the offset can be determined by solving the matrix.

[0008] To achieve the above objectives, the technical solutions provided by the present invention are:

[0009] A method for monitoring and controlling coupler offset for underwater wireless charging, comprising the following steps:

[0010] Step 1: Design the structure of the relay coil based on the coupler, including the following sub-steps:

[0011] Step 1.1: Determine the number, size, and array layout of the relay coils based on the size of the coupler's primary coil. The relay coils are arranged in a plane parallel to the primary coil.

[0012] Step 1.2, measure the self-inductance of the relay coil and calculate the compensation capacitance value of the relay coil based on the resonance condition;

[0013] Step 1.3, derive the expression for the relay coil current and determine that the relay coil current can represent the change in the mutual inductance coefficient between the relay coil and the coupler secondary coil;

[0014] Step 2, using BP neural network to perform offset solution, includes the following sub-steps:

[0015] Step 2.1: Construct a BP neural network model. The model input is the current value of each relay coil. The number of nodes in the input layer is the same as the number of relay coils. The model output is the offset of the secondary side coil on the X, Y, and Z axes and the deflection in three directions. The number of nodes in the output layer is 6.

[0016] Step 2.2: Simulate the offset between the primary and secondary coils under various charging conditions, detect the offset amount under each offset condition and the corresponding current value of each relay coil, and use this as the data set for the BP neural network.

[0017] Step 2.3, use the obtained data set to train and verify the constructed BP neural network model to obtain the output and input solution matrix of the model;

[0018] Step 3: During the charging process, the current value of the relay coil is monitored in real time. Based on the collected current value, the offset direction and offset amount of the primary side coil and the secondary side coil are determined through the obtained solution matrix. The control mechanism of the primary side coil is controlled to adjust the position of the primary side coil so that it is aligned with the secondary side coil.

[0019] Furthermore, in step 1.1, the relay coil is designed as a coil array consisting of 9 annular coils, the diameter of the annular coil is 1 / 6 of the diameter of the primary side coil, and the coil array is arranged in a cross-shaped pattern.

[0020] Furthermore, in step 2.3, the BP neural network model is trained using the gradient descent method to obtain the solution matrix.

[0021] Furthermore, the coupler offset monitoring and control method also includes designing a control mechanism for the primary side coil, including the following steps:

[0022] Determine the maximum offset and accuracy of the coupler based on the simulated offset situation;

[0023] Select the electric push rod of the control mechanism according to the stroke and feed rate;

[0024] Determine the operating current and voltage of the electric linear actuator;

[0025] Design or select the motor controller of the control mechanism according to the working current and voltage of the electric linear actuator;

[0026] Jointly adjust the control parameters of the control mechanism and optimize the adjustment time of active control.

[0027] The advantages of the present invention are:

[0028] 1. The present invention relates to a coupler offset monitoring and control method for underwater wireless charging. A relay coil array is added to the middle of the wireless charging coupler. Its current can characterize the change in the mutual inductance between the relay coil and the coupler's secondary coil. A BP neural network is used to perform offset calculations, simulating the coupler's offset and deflection in various directions under various charging conditions. A solution matrix for the coupler offset and relay coil current is obtained. During the charging process, the coupler offset is determined based on the real-time detected relay coil current value. The primary coil is then adjusted for motion compensation to maintain precise coupling. Therefore, the relay coil provided by the present invention can enhance the coupling coefficient, expand the electromagnetic field transmission distance, and achieve passive anti-offset. Furthermore, the current parameters in the arrayed relay coils can be monitored, and offset and deflection detection can be achieved through coil array current sampling, enabling active anti-offset, thereby improving the efficiency and stability of underwater wireless charging.

[0029] 2. The present invention does not require any changes to the existing wireless charging coupler itself. The sampling and control system of the relay coil can be directly mounted on the wireless charging coupler independently of the power transmission system. It is applicable to various couplers and has strong adaptability.

[0030] 3. The relay coils in the present invention are arranged as a crisscross coil array consisting of 9 coils, which ensures the scale and density of the detection coils and improves the deviation detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and / or other features and advantages of the present invention will become more readily understood through the following description with reference to the accompanying drawings, which are not drawn to scale and in which some features are exaggerated or minimized to show details of particular components.

[0032] Figure 1 is a flow chart of a coupler offset monitoring and control method applicable to underwater wireless charging of the present invention;

[0033] Figure 2 is a schematic diagram of a coupler offset monitoring and control method applicable to underwater wireless charging according to the present invention;

[0034] Figure 3 This is a structural diagram of the relay coil in the present invention;

[0035] Figure 4 This is a diagram showing the positional arrangement of the relay coil and the primary side coil in the present invention;

[0036] Figure 5 This is an electromagnetic model diagram of the relay coil and coupler in the present invention;

[0037] Figure 6 is an equivalent circuit topology diagram of the relay coil and the coupler in the present invention;

[0038] Figure 7 It is a structural diagram of the BP neural network in the present invention;

[0039] Figure 8 Schematic diagram of the offset and alignment of the coupler during the docking process of the spacecraft in the example of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be described in detail below with reference to the accompanying drawings by means of exemplary embodiments of the present invention. It should be noted that the following detailed description of the present invention is only for the purpose of illustration and is not intended to limit the present invention.

[0041] The present invention provides a coupler offset monitoring and control method suitable for underwater wireless charging, which is used to correct the relative motion between the underwater vehicle and the charging base station when the underwater vehicle performs underwater wireless power transmission, so as to maintain precise coupling of the coupler and avoid the decrease in energy transmission efficiency or charging interruption caused by coupler offset.

[0042] First, the overall reference Figure 1 and Figure 2 As an exemplary embodiment of the present invention, a coupler offset monitoring and control method applicable to underwater wireless charging includes the following steps:

[0043] Step S1, designing a relay coil structure according to the coupler, wherein the relay coil is arranged in a plane parallel to the primary coil, and determining the relay coil current to represent the change in the mutual inductance coefficient between the relay coil and the secondary coil of the coupler;

[0044] Step S2, using BP neural network to perform offset solution to obtain a solution matrix of coupler offset and relay coil current;

[0045] In step S3, during the charging process, the current value of the relay coil is monitored in real time. Based on the collected current value, the offset direction and offset amount of the primary side coil and the secondary side coil are determined through the obtained solution matrix. The control mechanism of the primary side coil is used to adjust the position of the primary side coil so that it performs motion compensation and aligns with the secondary side coil, thereby ensuring that the coupler maintains precise coupling.

[0046] A wireless charging relay coil is a technical component used to enhance wireless charging efficiency and range. It receives the electromagnetic field from the wireless charging transmitter, concentrates the magnetic field, and converts it into electric current, which is then transmitted to the receiving device. Placed between the primary and secondary couplers, the relay coil improves the coupling coefficient and increases the effective transmission distance of wireless charging. This is known as passive anti-skew, which enhances charging efficiency.

[0047] Reference Figure 3Each relay coil consists of a Litz coil, a resonant capacitor, and an alternating current detection module. The detected alternating current is transmitted to the data bus via a shielded cable. The shielded cable is used to prevent the rapidly changing electromagnetic field between the power coils from interfering with the data.

[0048] Step S1 may include: Step S1.1, determining the number, size, and array arrangement structure of the relay coils according to the size of the primary side coil.

[0049] like Figure 4 As shown, the present invention is explained by taking a planar coupler circular coil as an example, and an arrayed relay coil is used to form a detection plane. The detection plane is parallel to the coil plane where the primary side coil of the coupler used to transmit power is located. All relay coils are in the detection plane and are spaced 10-20 mm apart from the coil plane.

[0050] In order to ensure the omnidirectionality of offset detection and improve the accuracy of offset detection, the relay coil can be designed as a coil array consisting of 9 annular coils. The diameter of the annular coil is 1 / 6 of the diameter of the primary side coil, and the coil array is arranged in a "M" shape. Except for the relay coil DET0 at the center of the coupler, the remaining 8 relay coils are arranged in a "M"-shaped array and evenly dispersed around the periphery of coil DET0. The relay coil diameter is selected to be smaller because, in the present invention, the relay coil is mainly used to detect the offset for active anti-offset, and enhancing the coupling coefficient is only an auxiliary role. The small size and large number of arrangements can ensure the scale and density of the detection coils and improve the detection accuracy of the offset.

[0051] Step S1 also includes: step S1.2, measuring the self-inductance of the relay coil and calculating the compensation capacitance value of the relay coil according to the resonance condition; step S1.3, deriving the expression of the relay coil current, and determining that the current of the relay coil can represent the change of the mutual inductance coefficient between the relay coil and the secondary side coil of the coupler.

[0052] The relay coil array used in the present invention is in the same detection plane, and its diameter is small, the relative distance is far, and the relative facing area is 0, so the mutual inductance between the relay coils can be ignored. The overall modeling is as follows Figure 5 As shown. In order to simplify the system, the SSS compensation topology is adopted, that is, the primary side, secondary side, and relay coil all adopt the series compensation method. Its equivalent circuit topology is as follows Figure 6 shown.

[0053] Since coupler offset will cause the mutual inductance of the coil array to change, it is first demonstrated that the relay coil current detection can reflect the mutual inductance change, and there is a unique representation relationship between the relay coil current and the mutual inductance.

[0054] According to Kirchhoff's voltage law and the equivalent circuit topology model, the following equation can be derived:

[0055]

[0056] Where, is the AC output voltage of the primary-side inverter; j is a complex unit; ω represents the circuit frequency; Z P 、Z S and Z i are the equivalent impedances of the primary side, secondary side and relay coil respectively; and are the currents of the primary side, secondary side and relay coil respectively; M PS is the mutual inductance of the primary and secondary coils, M Pi is the mutual inductance between the primary coil and a single relay coil, M iS It is the mutual inductance between the relay coil and the secondary coil.

[0057] Solving the above equation, we can get the expression of the required relay coil current. The relay coil current is:

[0058]

[0059] Considering the case of complete resonance, Z P =R P ,Z S =R L ,Z i =R i , R P is the primary side equivalent series resistance, R L is the equivalent resistive load, R i is the internal resistance of the relay coil. P and R i It is only the line resistance, which is very small, only in the milliohm level, and can be approximately considered to be 0. Therefore, the above formula can be simplified to be equivalent.

[0060]

[0061] Since the position of the relay coil relative to the primary coil does not change, M Pi It is also a constant, and there is only one variable M in the formula iS , M iS is the mutual inductance between the relay coil and the secondary coil. When the coupler is offset, M iS will change. β=2jω 3 M Pi M PS ,γ=ω 2 M PS 2 R L , then This shows that by measuring the current of the relay coil, the change in the mutual inductance coefficient between the relay coil and the secondary coil can be reflected, thereby reflecting the relative position of the primary and secondary coils.

[0062] In the case of complete resonance, the following relationship holds:

[0063]

[0064] Where C P is the primary side coil capacitance, C S is the secondary side coil capacitance, C i is the capacitance of the relay coil; L P is the self-inductance of the primary coil, L S is the self-inductance of the secondary coil, L i is the self-inductance of the relay coil. When the primary coil and the secondary coil are determined, the compensation capacitors, i.e. the primary coil capacitance C, can be solved separately. P , secondary side coil capacitance C S and relay coil capacitance C i size.

[0065] Step S2 includes step S2.1: constructing a BP neural network model, such as Figure 7 As shown in the figure, the model input is the current value of each relay coil. The number of nodes in the input layer is the same as the number of relay coils. The model output is the offset of the secondary coil on the X, Y, and Z axes, as well as the deflection in three directions. The number of nodes in the output layer is 6. To ensure fitting accuracy and prevent overfitting, the number of nodes in the hidden layer can be set to 10.

[0066] Step S2 also includes step S2.2: simulating the offset between the primary and secondary coils under various charging conditions, detecting the offset amount and the corresponding current value of each relay coil under each offset condition, and using this as a data set for the BP neural network. In this step, the secondary coil can be manually moved to simulate various offsets.

[0067] Step S2 also includes step S2.3: using the acquired data set to train and validate the constructed BP neural network model, obtaining a solution matrix for the model's output and input. Specifically, the BP neural network model can be trained using a gradient descent method to obtain the solution matrix. The solution matrix can be saved in the controller ROM and used to calculate the offset after detecting the relay coil array current parameters.

[0068] For step S3, Figure 2As shown, the current value of the relay coil can be transmitted to the processor via the data bus. The processor determines the offset direction and offset distance of the secondary coil relative to the primary coil based on the solution matrix. Since the primary coil is movably connected to the base via an electric push rod, the motor controller can control the electric push rod to adjust the position of the primary coil. Therefore, after determining the offset, the controller can calculate the motor control parameters of the primary coil. The control mechanism of the primary coil can control the primary coil to perform motion compensation based on these parameters, so that the primary coil and the secondary coil are aligned, thereby ensuring that the coupler maintains precise coupling. This active control process is called active anti-offset, which can improve the efficiency and stability of wireless charging.

[0069] In some embodiments, the coupler offset monitoring and control method of the present invention further includes designing a control mechanism for the primary-side coil, including the following steps: determining the maximum offset and accuracy of the coupler based on simulated offset conditions; selecting an electric actuator for the control mechanism based on stroke and feed rate; determining the operating current and voltage of the electric actuator; designing or selecting a motor controller for the control mechanism based on the operating current and voltage of the electric actuator; and jointly adjusting the control parameters of the control mechanism to optimize the adjustment time of the active control. Thus, a suitable control structure can be selected to achieve motion control of the primary-side coil.

[0070] Therefore, the relay coil provided by the present invention can not only enhance the coupling coefficient, expand the electromagnetic field transmission distance, and achieve passive anti-drift, but also monitor the current parameters in the arrayed relay coils, achieve offset and deflection detection through coil array current sampling, and perform active anti-drift, thereby improving the efficiency and stability of underwater wireless charging. This offset detection method can effectively improve the docking accuracy of underwater vehicles when approaching and docking, and suppress coupler offset during charging, ensuring efficient and safe charging. Furthermore, the present invention does not require changes to the existing wireless charging coupler itself. The sampling and control system of the relay coil can be directly mounted on the wireless charging coupler independently of the power transmission system, making it applicable to various couplers and highly adaptable. Primary-side mechanical motion control through the relay coil eliminates the need for secondary-side control, reducing the design cost of the secondary-side vehicle end and adapting to a variety of vehicle types. Furthermore, the offset monitoring and control method of the present invention does not require establishing a communication link between the primary and secondary sides, avoiding delays caused by poor wireless communication in water and improving the control rate.

[0071] Next, the coupler offset monitoring and control method applicable to underwater wireless charging provided by the present invention is further described with reference to examples.

[0072] Reference Figure 8As the spacecraft approaches the base station for docking, the secondary coil on the spacecraft is offset from the primary coil at the base station. This offset is characterized by a large offset distance and directional correction. Suppose the spacecraft deviates to the lower left of the base station as it approaches. During docking, the base station activates the energy transfer coil at short intervals, generating a pulsed electromagnetic field that is captured by the relay coil. Based on the mutual inductance between the relay coil and the secondary coil (which reflects their relative position), the relay coil generates induced currents of varying magnitudes. In this scenario, the secondary coil is closer to the lower left corner. In order of relative distance from the secondary coil, they should be DET6, DET5, DET0, DET7, DET8, DET4, DET1, DET3, and DET2. Based on the formula above, the currents of the relay coils at this point also follow the aforementioned order. Taking the first and last positions of the queue, the unique straight line between the two corresponding relay coils is the offset direction of docking between the spacecraft and the base station. The difference in current between the first and last positions reflects the offset magnitude.

[0073] Then, according to the determined coupler offset direction and offset size, the control mechanism of the primary side coil can be controlled to align the primary side coil with the secondary side coil. At the same time, the coupler offset during charging can be suppressed to ensure that the coupler maintains precise coupling during the charging process of the aircraft, ensuring efficient and safe charging.

[0074] Finally, it should be noted that the features mentioned and / or illustrated in the above description of the exemplary embodiments of the present invention may be incorporated into one or more other embodiments in the same or similar manner, combined with features in other embodiments, or substituted for corresponding features in other implementations. The technical solutions obtained by such combinations or substitutions shall also be deemed to be included within the scope of protection of the present invention.

Claims

1. A coupler offset monitoring and control method suitable for underwater wireless charging, characterized in that: The following steps are involved: Step 1: Design the structure of the relay coil based on the coupler, including the following sub-steps: Step 1.1: Determine the number, size, and array layout of the relay coils based on the size of the coupler's primary coil. The relay coils are arranged in a plane parallel to the primary coil. Step 1.2, measure the self-inductance of the relay coil and calculate the compensation capacitance value of the relay coil based on the resonance condition; Step 1.3, derive the expression for the relay coil current and determine that the relay coil current can represent the change in the mutual inductance coefficient between the relay coil and the coupler secondary coil; Step 2, using BP neural network to perform offset solution, includes the following sub-steps: Step 2.1: Construct a BP neural network model. The model input is the current value of each relay coil. The number of nodes in the input layer is the same as the number of relay coils. The model output is the offset of the secondary side coil on the X, Y, and Z axes and the deflection in three directions. The number of nodes in the output layer is 6. Step 2.2: Simulate the offset between the primary and secondary coils under various charging conditions, detect the offset amount under each offset condition and the corresponding current value of each relay coil, and use this as the data set for the BP neural network. Step 2.3, use the obtained data set to train and verify the constructed BP neural network model to obtain the output and input solution matrix of the model; Step 3: During the charging process, the current value of the relay coil is monitored in real time. Based on the collected current value, the offset direction and offset amount of the primary side coil and the secondary side coil are determined through the obtained solution matrix. The control mechanism of the primary side coil is controlled to adjust the position of the primary side coil so that it is aligned with the secondary side coil.

2. The method for monitoring and controlling coupler offset for underwater wireless charging according to claim 1, wherein: In step 1.1, the relay coil is designed as a coil array consisting of 9 annular coils, the diameter of the annular coil is 1 / 6 of the diameter of the primary side coil, and the coil array is arranged in a cross shape.

3. The coupler offset monitoring and control method for underwater wireless charging according to claim 1 or 2, characterized in that: In step 2.3, the BP neural network model is trained using the gradient descent method to obtain the solution matrix.

4. The coupler offset monitoring and control method for underwater wireless charging according to claim 1 or 2, characterized in that It also includes the design of the control mechanism for the primary side coil, including the following steps: Determine the maximum offset and accuracy of the coupler based on the simulated offset situation; Select the electric push rod of the control mechanism according to the stroke and feed rate; Determine the operating current and voltage of the electric linear actuator; Design or select the motor controller of the control mechanism according to the working current and voltage of the electric linear actuator; Jointly adjust the control parameters of the control mechanism and optimize the adjustment time of active control.

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