Coupler offset monitoring and control method suitable for underwater wireless charging

Abstract

The invention provides a coupler offset monitoring and control method suitable for underwater wireless charging, and the method comprises the steps: designing the structure of a repeating coil according to a coupler, and determining that the current of the repeating coil can represent the mutual inductance coefficient change of the repeating coil and a secondary side coil; utilizing a BP neural network to obtain a resolving matrix of the coupler offset and the relay coil current; in the charging process, according to the collected current value, the offset direction and offset of the primary side coil and the secondary side coil are determined through a resolving matrix, a control mechanism of the primary side coil is controlled to be aligned with the secondary side coil, and therefore it is guaranteed that the coupler keeps accurate coupling. According to the relay coil, the coupling coefficient can be enhanced, the electromagnetic field transmission distance can be expanded, passive anti-offset can be achieved, current parameters in the array relay coil can serve as monitoring objects, offset and deflection detection can be achieved through coil array current sampling, active anti-offset is conducted, and the underwater wireless charging efficiency and stability are improved.

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 are important tools for underwater development and exploration, and are currently used in many industries. Their limited space limits the amount of electrical energy they can carry, and the continuity of underwater operations is a bottleneck in the development of underwater vehicles. Underwater wireless charging technology transfers energy through the electromagnetic field between coupling coils, requiring only a small space to quickly recharge underwater energy for the vehicle, which can significantly enhance the vehicle's ability 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 stopping"; Second, after docking, the coupler will be offset by the impact of ocean currents, and 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, and promptly correct the relative motion between the vehicle and the charging base station. It can 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 matching a small receiver, but 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 for 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 simplifies it to a three-degree-of-freedom translation, but these methods all ignore the coupler deflection problem that often occurs in underwater docking charging, so 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 problem that the offset control of the underwater wireless charging coupler in the prior art cannot achieve active anti-offset and cannot detect the deflection of the coupler, and provide a coupler offset monitoring and control method suitable for underwater wireless charging. By adding a relay coil array in the middle of the wireless charging coupler and sampling it, the coupling coefficient can be enhanced and the electromagnetic field transmission distance can be expanded to achieve passive anti-offset. The current parameters in the arrayed relay coil can be used as the monitoring object, and the offset and deflection detection can be achieved through the coil array current sampling, so as to perform active anti-offset.

[0007] Furthermore, the applicant found that, unlike the offset when the spacecraft approaches and docks, the offset that occurs during the docking and charging process of the spacecraft has the characteristics of small offset, slow speed and uncertain direction. During the simulation design and experimental process, the applicant found that the offset during the charging process is difficult to determine through a single detection, and requires rapid multiple detections and rapid identification to obtain the offset situation. In response to this new problem, the applicant considered using a convolutional neural network to obtain the solution matrix of the offset and current, that is, the offset situation can be determined by solving the matrix after detecting the current parameters of the relay coil array.

[0008] To achieve the above purpose, the technical solution provided by the present invention is:

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

[0010] Step 1, designing the structure of the relay coil according to the coupler, including the following sub-steps:

[0011] Step 1.1, according to the size of the primary side coil of the coupler, determine the number, size and array arrangement structure of the relay coils, and the relay coils are arranged in a plane parallel to the primary side coil;

[0012] Step 1.2, measuring the self-inductance of the relay coil and calculating the compensation capacitance value of the relay coil according to the resonance condition;

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

[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 around three directions. The number of nodes in the output layer is 6.

[0016] Step 2.2, simulating the offset of the primary side coil and the secondary side coil under various charging conditions, detecting the offset amount under each offset condition and the corresponding current value of each relay coil as a data set for the BP neural network;

[0017] Step 2.3, using the obtained data set to train and verify the constructed BP neural network model, and 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, and the offset direction and offset amount of the primary side coil and the secondary side coil are determined by the obtained solution matrix according to the collected current value, and 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 shape.

[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 actuator;

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

[0026] Coordinate 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 coupler offset monitoring and control method suitable for underwater wireless charging of the present invention adds a relay coil array in the middle of the wireless charging coupler, whose current can characterize the change of the mutual inductance coefficient between the relay coil and the secondary coil of the coupler, uses the BP neural network to perform offset solution, simulates the offset and deflection of the coupler in various directions under various charging conditions, obtains the solution matrix of the coupler offset and the relay coil current, and during the charging process, after determining the coupler offset according to the real-time detected relay coil current value, adjusts the primary side coil for motion compensation, so that the coupler maintains precise coupling. Therefore, the relay coil provided by the present invention can not only enhance the coupling coefficient, expand the electromagnetic field transmission distance, and realize passive anti-offset, but also can use the current parameters in the arrayed relay coil as the monitoring object, realize offset and deflection detection through coil array current sampling, and perform active anti-offset, thereby improving the efficiency and stability of underwater wireless charging.

[0029] 2. The present invention does not need to change the existing wireless charging coupler itself, and can directly hang the sampling and control system of the relay coil on the wireless charging coupler independently of the power transmission system. It can be applied to various couplers and has strong adaptability.

[0030] 3. The relay coil in the present invention is arranged as a cross-shaped coil array consisting of 9 coils, which ensures the scale and density of the detection coil 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 easily understood through the following description with reference to the accompanying drawings, which are not drawn to scale and some features are exaggerated or reduced to show details of specific components. In the accompanying drawings:

[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 of the present invention;

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

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

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

[0037] Figure 6 It 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 It is a 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 that the coupler maintains precise coupling and avoids the decrease of 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 the structure of the relay coil according to the coupler, the relay coil is arranged in a plane parallel to the primary side coil, and determining the relay coil current can characterize the change of the mutual inductance coefficient between the relay coil and the secondary side 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] Step S3, during the charging process, the current value of the relay coil is monitored in real time, and the offset direction and offset amount of the primary side coil and the secondary side coil are determined by the obtained solution matrix according to the collected current value, and the control mechanism of the primary side coil is controlled 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] The wireless charging relay coil is a technical component used to enhance the efficiency and range of wireless charging. It can receive the electromagnetic field from the wireless charging transmitter, play the role of converging the magnetic field, and convert it into current, and then transmit the current to the receiving device. The relay coil is placed between the primary and secondary side couplers, which can improve the coupling coefficient and increase the effective transmission distance of wireless charging. This is passive anti-deviation, which can enhance charging efficiency.

[0047] Reference Figure 3Each relay coil consists of a Litz coil, a resonant capacitor and an alternating current detection module, and transmits the detected alternating current to the data bus through a shielded line. The shielded line 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 10-20mm apart from the coil plane.

[0050] In order to ensure the omnidirectionality of the offset detection and improve the accuracy of the 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 in the center of the coupler, the other 8 relay coils are arranged in a "M"-shaped array and evenly dispersed around the periphery of the 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 arrangement structures 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 characterize 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 are all compensated in series. The equivalent circuit topology is as follows Figure 6 shown.

[0053] Since the 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 change of mutual inductance, 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] In the formula, is the AC output voltage of the primary 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 for 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, and its value is very small, only at the milliohm level, and is approximately considered to be 0. Therefore, the above formula can be simplified equivalently.

[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 It shows that by measuring the current of the relay coil, the change of 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] In the formula, C P is the primary coil capacitance, C S is the secondary 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 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 and the deflection in three directions, and the number of nodes in the output layer is 6. In order to ensure the fitting accuracy and prevent overfitting, the number of nodes in the hidden layer can be selected as 10.

[0066] Step S2 also includes step S2.2: simulating the offset of the primary coil and the secondary coil under various charging conditions, detecting the offset amount under each offset condition and the corresponding current value of each relay coil as a data set of 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 obtained data set to train and verify the constructed BP neural network model to obtain the output and input solution matrix of the model. In particular, the gradient descent method can be used to train the BP neural network model to obtain the solution matrix. The solution matrix can be saved in the controller ROM, that is, the offset can be calculated through the matrix after the relay coil array current parameters are detected.

[0068] For step S3, Figure 2As shown, the current value of the relay coil can be transmitted to the processor through the data bus, and the processor determines the offset direction and offset distance of the secondary side coil relative to the primary side coil based on the solution matrix. Since the primary side 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 side coil. Therefore, after determining the offset, the controller can calculate the motor control parameters of the primary side coil, and the control mechanism of the primary side coil can control the primary side coil to perform motion compensation based on the parameters, so that the primary side coil is aligned with the secondary side coil, thereby ensuring that the coupler maintains precise coupling. This active control process is 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 also includes the design of a control mechanism for the primary side coil, including the following steps: determining the maximum offset and accuracy of the coupler according to the simulated offset; selecting the electric push rod of the control mechanism according to the stroke and feed amount; determining the working current and voltage of the electric push rod; designing or selecting the motor controller of the control mechanism according to the working current and voltage of the electric push rod; 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 realize the 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-deviation, but also can use the current parameters in the arrayed relay coil as the monitoring object, realize the offset and deflection detection through the coil array current sampling, and perform active anti-deviation, thereby improving the efficiency and stability of underwater wireless charging. Through this offset detection method, the docking accuracy of the underwater vehicle can be effectively improved when the underwater vehicle approaches and docks, and the coupler offset during the charging process can be suppressed during charging to ensure efficient and safe charging. In addition, the present invention does not need to change the existing wireless charging coupler itself, and can directly hang the sampling and control system of the relay coil on the wireless charging coupler independently of the power transmission system, which can be applied to various couplers and has strong adaptability. The primary side mechanical motion control is performed by the relay coil, and the secondary side does not need to be controlled, which reduces the design cost of the secondary side vehicle end, and can be adapted to various types of vehicles. In addition, the offset monitoring and control method of the present invention does not need to establish a communication link between the primary and secondary sides, avoids the delay caused by poor wireless communication in water, and improves 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 8, when the aircraft approaches the base station for docking, the secondary coil on the aircraft is offset from the primary coil at the base station. This type of offset has the characteristics of large offset distance and directional offset correction process. Assume that the aircraft is biased to the lower left side of the base station when approaching the base station. During the docking process, the base station turns on the energy transmission coil at a short time interval to generate a pulse electromagnetic field, which is captured by the relay coil. The relay coil generates different induced currents based on the mutual inductance coefficient between the relay coil and the secondary coil (which can reflect the relative position). As shown in the figure, the secondary coil is closer to the lower left corner. According to the relative distance from the secondary side, it should be DET6, DET5, DET0, DET7, DET8, DET4, DET1, DET3, DET2. According to the above formula, the current size of each relay coil is also the above order. Take the head and tail of the above queue. The only straight line where the corresponding two relay coils are located is the offset direction of the docking between the aircraft and the base station. The current difference between the head and tail of the queue reflects the offset size.

[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 shown in the above description of the exemplary embodiments of the present invention may be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or substituted for the corresponding features in other implementations. The technical solutions obtained by these combinations or substitutions shall also be deemed to be included in the protection scope 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, designing the structure of the relay coil according to the coupler, including the following sub-steps: Step 1.1, according to the size of the primary side coil of the coupler, determine the number, size and array arrangement structure of the relay coils, and the relay coils are arranged in a plane parallel to the primary side coil; Step 1.2, measuring the self-inductance of the relay coil and calculating the compensation capacitance value of the relay coil according to the resonance condition; Step 1.3, derive the expression of the relay coil current, and determine that the current of the relay coil can represent the change of the mutual inductance coefficient between the relay coil and the secondary coil of the coupler; 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 around three directions. The number of nodes in the output layer is 6. Step 2.2, simulating the offset of the primary side coil and the secondary side coil under various charging conditions, detecting the offset amount under each offset condition and the corresponding current value of each relay coil as a data set for the BP neural network; Step 2.3, using the obtained data set to train and verify the constructed BP neural network model, and 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, and the offset direction and offset amount of the primary side coil and the secondary side coil are determined by the obtained solution matrix according to the collected current value, and 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 coupler offset monitoring and control method for underwater wireless charging according to claim 1, characterized in that: 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 a 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 a 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 actuator; Design or select the motor controller of the control mechanism according to the working current and voltage of the electric actuator; Coordinate the control parameters of the control mechanism and optimize the adjustment time of active control.

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