Multi-converter underwater wireless power transmission system based on optimal current control and efficiency optimization method thereof

Abstract

The application discloses a multi-converter underwater wireless power transmission system based on optimal current control and an efficiency optimization method thereof. The method comprises the following steps: sampling rectification side current output current and output voltage, calculating a first mutual inductance and a first load; according to the identified mutual inductance output power and system parameters, calculating optimal primary side coil current of the inverter side and optimal secondary side coil current of the rectification side; according to the optimal primary side coil current and the optimal secondary side coil current, calculating a phase shift angle of the first inverter unit and a duty cycle of the first rectification unit; according to the comparison between the sampled output current and output voltage and the set value, fine-tuning the phase shift angle and the duty cycle; sampling the rectification side current, the output current and the output voltage again, calculating a second mutual inductance and a second load; when the second mutual inductance is equal to the first mutual inductance and the second load is equal to the first load, the system works in a constant current constant voltage high efficiency charging mode. The application realizes wide range and high efficiency charging of underwater constant current constant voltage.

Description

Technical Field

[0001] This invention relates to the field of underwater wireless power transfer and charging control technology, and in particular to a multi-converter underwater wireless power transfer system based on optimal current control and its efficiency optimization method. Background Technology

[0002] With the rapid development of underwater intelligent equipment, its energy supply has received increasing attention. Traditional wired charging methods require direct contact with electrical connectors, which has disadvantages such as inconvenient plugging and unplugging, easy corrosion of interfaces, and high requirements for insulation and sealing, making them unsuitable for complex underwater environments. Wireless power transfer technology can achieve power transfer in a non-contact manner, with advantages such as high security, high reliability, and strong adaptability, thus becoming an important development direction for charging underwater intelligent equipment.

[0003] However, existing underwater wireless power transfer technologies still have the following problems: First, existing systems typically require additional DC-DC converters or complex multi-stage power conversion structures during wide-range output adjustment, leading to increased system size, higher costs, and more complex control. Second, relative misalignment can easily occur between the transmitter and receiver in the underwater environment, causing changes in coupling inductance and resulting in fluctuations in output power and charging status. Third, the conductivity of seawater introduces additional eddy current losses, further reducing system efficiency. Fourth, existing solutions struggle to simultaneously achieve high-efficiency operation and constant current / constant voltage charging requirements under varying load and location conditions.

[0004] Therefore, there is an urgent need for a new underwater wireless power transfer system and control method to reduce system complexity, improve power regulation range and transmission efficiency, and enhance the system's stable charging capability under conditions of coupling changes and load disturbances. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-converter underwater wireless power transfer system based on optimal current control and its efficiency optimization method, so as to solve at least one of the above-mentioned technical problems.

[0006] The preferred technical solutions among the many technical solutions provided by this invention can produce a variety of technical effects, which are described in detail below.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control. In the multi-converter underwater wireless power transfer system, except for the first inverter unit and the first rectifier unit, the phase shift angles of the remaining inverter units are fixed, and the duty cycles of the remaining rectifier units are fixed. The method includes: S100: Identify the first mutual inductor and the first load by sampling the output current, output voltage and rectifier side current; S200. Based on the identified mutual inductance, output power, and system parameters, calculate the optimal primary winding current on the inverter side and the optimal secondary winding current on the rectifier side. S300. Calculate the phase shift angle of the first inverter unit and the duty cycle of the first rectifier unit based on the optimal primary coil current and the optimal secondary coil current. S400. Based on the relationship between the sampled output current and output voltage and the set reference output current and reference output voltage, fine-tune the calculated phase shift angle and duty cycle. S500: Sample output current, output voltage and rectified side current to identify the second mutual inductor and the second load; S600: If the second mutual inductance is not equal to the first mutual inductance or the second load is not equal to the first load, return to step S200; if the second mutual inductance is equal to the first mutual inductance and the second load is equal to the first load, determine whether the output current and the output voltage have reached the set values. If so, maintain the current state of efficient charging; otherwise, return to step S400.

[0008] In one or more embodiments, step S400 includes the following steps: Based on the sampled output current and output voltage, as well as the reference output current and reference output voltage, determine whether the entire system is in constant current mode or constant voltage mode; When in constant current mode, if the output current is less than the reference output current, the phase angle and duty cycle are calculated by a slight increase according to a set setting; if the output current is greater than the reference output current, the phase angle and duty cycle are calculated by a slight decrease according to a set setting. When in the constant voltage mode, if the output voltage is less than the reference output voltage, the phase shift angle and duty cycle are calculated by slightly increasing the set value; if the output voltage is greater than the reference output voltage, the phase shift angle and duty cycle are calculated by slightly decreasing the set value.

[0009] In one or more embodiments, the mutual inductance between the inverter side and the rectifier side Identified by the following expression: ; in, ω The system's operating angular frequency, This is the sum of the leakage inductance of the inverter-side transformer. This is the sum of the leakage inductance of the rectifier-side transformer. This is the inverter-side voltage. This is the rectifier-side current.

[0010] In one or more embodiments, the optimal primary coil current The following formula is used to obtain: ; in, X 1 represents the intermediate variable corresponding to the internal resistance of the primary coil and the internal resistance of the inverter side. X 2 represents the intermediate variables corresponding to the internal resistance of the secondary coil and the internal resistance of the rectifier side. E 1 represents the eddy current loss component corresponding to the primary coil. F It is an intermediate variable for the eddy current loss component corresponding to the secondary coil.

[0011] In one or more embodiments, the optimal secondary coil current The following formula is used to obtain: ; in, This refers to the output power.

[0012] In one or more embodiments, the phase shift angle of the first inverter unit is calculated. Duty cycle of the first rectifier unit The mathematical expressions are as follows: ; ; in, Input voltage, This represents the number of inverter units. This refers to the turns ratio of the inverter-side transformer. For output voltage, The number of rectifier units. This represents the turns ratio of the rectifier-side transformer.

[0013] In one or more embodiments, the first load and the second load are identified by corresponding sampled output current and output voltage.

[0014] In one or more embodiments, the method further includes establishing a total system loss model after obtaining mutual inductance and output power, and determining an optimal transmission current with the goal of minimizing the total system loss; the total system loss includes circuit loss and seawater eddy current loss; the circuit loss includes power device conduction loss, coil loss, rectification loss, and resonant inductor integrated transformer loss.

[0015] According to another aspect of the present invention, a multi-converter underwater wireless power transfer system based on optimal current control is also provided, comprising a first inverter unit and a first rectifier unit as described in the above-described efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control, and other inverter units and other rectifier units; the first inverter unit and the other inverter units are connected in parallel, with their parallel input terminals connected to an input power supply, and the first rectifier unit and the other rectifier units are connected in parallel, with their parallel output terminals connected to an electronic load; the first inverter unit and the other inverter units constitute the inverter side, and the first rectifier unit and the other rectifier units constitute the rectifier side; It also includes a transformer disposed between the inverter side and the rectifier side, a base station-side resonant compensation network integrated into the primary side transmitting coil of the transformer, an equipment-side resonant compensation network integrated into the secondary side receiving coil of the transformer, the output terminals of the first inverter unit and the remaining inverter units being connected to the base station-side resonant compensation network, and the input terminals of the first rectifier unit and the remaining rectifier units being connected to the equipment-side resonant compensation network.

[0016] In one or more embodiments, the first inverter unit includes a capacitor C1, a field-effect transistor (FET) S11, a field-effect transistor (FET) S21, a field-effect transistor (FET) S31, and a field-effect transistor (FET) S41; one plate of capacitor C1, the drain of FET S11, and the drain of FET S21 are all connected to one terminal of the input power supply, and the other plate of capacitor C1, the source of FET S31, and the source of FET S41 are all connected to the other terminal of the input power supply; the source of FET S11 and the drain of FET S31 are connected together, and the source of FET S21 and the drain of FET S41 are connected together. The base station-side resonance compensation network includes capacitor C. f_ga Capacitor C ga Capacitor C f_ga One plate, capacitor C ga One of the plates is connected to the emitter coil L. ga At both ends, capacitor C f_ga The other plate, capacitor C ga The other plate is connected to the source of the field-effect transistor S11 and the drain of the field-effect transistor S31; The remaining inverse conversion units are all DC-AC inverters. The positive and negative input terminals of each DC-AC inverter are connected to the positive and negative terminals of the input power supply, respectively. The output terminal of each DC-AC inverter is connected to the two ends of the primary winding of a transformer. The secondary windings of the transformer connected to each DC-AC inverter are connected in series. One end of the series connection is connected between MOSFETs S21 and S41, and the other end is connected to the emitter coil L. ga Capacitor C f_ga between; The first rectifier unit includes a field-effect transistor Q11, a field-effect transistor Q21, a diode D11, and a diode D21. The source of field-effect transistor Q11 and the source of field-effect transistor Q21 are connected to the positive terminal of the electronic load, and the negative terminals of diode D11 and the negative terminal of diode D21 are connected to the negative terminal of the electronic load. The equipment-side resonance compensation network includes capacitor C. f_va Capacitor C va Capacitor C f_va One plate, capacitor C va One of the plates is connected to the receiving coil L. va At both ends, capacitor C f_va The other plate, capacitor C va The other plate is connected to the drain of the field-effect transistor Q11 and the positive terminal of the diode D11; The remaining rectifier units are all AC-DC rectifiers. The positive output terminal of each AC-DC rectifier is connected to the positive terminal of the electronic load, and the negative output terminal of each AC-DC rectifier is connected to the negative terminal of the electronic load. The input terminals of each AC-DC rectifier are respectively connected to the two ends of the primary winding of a transformer. The secondary windings of the transformer to which each AC-DC rectifier is connected are connected in series. One end of the series connection is connected between the field-effect transistor Q21 and the diode D21, and the other end of the series connection is connected to the capacitor C. f_va Receiver coil L va between.

[0017] Implementing one of the above-described technical solutions of the present invention has the following advantages or beneficial effects: This invention applies optimal control parameters to the first inverter unit and the first rectifier unit, while the remaining auxiliary conversion units maintain preset fixed operating states, thereby bringing the system close to its theoretical optimal efficiency point. Simultaneously, through mutual inductance, load identification, and total loss optimization, the control quantities of key conversion units are jointly adjusted, achieving wide-range power transmission while ensuring high-efficiency operation and constant-current / constant-voltage charging control, demonstrating significant engineering application value. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a flowchart of an efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control, according to an embodiment of the present invention. Figure 2This is a circuit diagram of a multi-converter underwater wireless power transfer system based on optimal current control according to an embodiment of the present invention; Figure 3 This is an equivalent circuit diagram of a multi-converter underwater wireless power transfer system based on optimal current control, according to an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, various exemplary embodiments described below will be referenced to the accompanying drawings, which form part of the exemplary embodiments, illustrating various exemplary embodiments that may be used to implement the present invention. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. It should be understood that they are merely examples of processes, methods, and apparatuses consistent with some aspects of the present invention disclosed as detailed in the appended claims, and other embodiments may be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and spirit of the present invention.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the referred element must have a specific orientation, or be constructed and operated in a specific orientation. The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. The term "a plurality" means two or more. The terms "connected" and "linked" should be interpreted broadly, for example, they can refer to fixed connections, detachable connections, integral connections, mechanical connections, electrical connections, communication connections, direct connections, indirect connections through an intermediate medium, and can refer to the internal communication of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more of the related listed items. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] To illustrate the technical solution described in this invention, specific embodiments are described below, showing only the parts related to the embodiments of this invention.

[0022] Example 1: As Figure 1 , Figure 2As shown, this embodiment provides an efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control. The multi-converter underwater wireless power transfer system includes m inverter units and n rectifier units. Except for the first inverter unit (#1 inverter unit in the figure) and the first rectifier unit (#1 rectifier unit in the figure), the phase shift angles of the remaining inverter units (#2 inverter unit, ..., #m inverter unit) are fixed, and the duty cycles of the remaining rectifier units (#2 rectifier unit, ..., #n rectifier unit) are fixed.

[0023] In a specific embodiment, the phase shift angle of the remaining inverse transform units is fixed at 1. α i =90° i=2,…,m The duty cycle of the remaining rectifier units is fixed at ), D j =0.5 ( j=2,…,n ).

[0024] Based on the above embodiments, by adjusting only the phase shift angle of the first inverter module... α 1 and the duty cycle of the first rectifier module D 1. This can reduce control complexity while optimizing system current distribution and improving efficiency.

[0025] The efficiency optimization methods for the above-mentioned multi-converter underwater wireless power transfer system include: S100 identifies the first mutual inductor and the first load by sampling the output current, output voltage and rectifier side current.

[0026] In one or more embodiments, the mutual inductance between the inverter side and the rectifier side Identified by the following expression: (1); in, ω The system's operating angular frequency, This is the sum of the leakage inductance of the inverter-side transformer. This is the sum of the leakage inductance of the rectifier-side transformer. The inverter-side voltage (see formula (6)). The rectifier side current (corresponding to) Figure 2 (Irec).

[0027] It should be noted that mutual inductance includes the first mutual inductance mentioned above and the second mutual inductance mentioned below, both of which are obtained through corresponding steps.

[0028] In a specific embodiment, ω =2π f , f The operating frequency is set to 85.5 kHz.

[0029] In one or more embodiments, the load (equivalent load) is obtained by sampling the output current and output voltage, where load = output voltage / output current. The load includes a first load and a second load (see below), identified by the output current and output voltage sampled in the corresponding steps.

[0030] S200. Based on the identified mutual inductance, output power, and system parameters, calculate the optimal primary winding current on the inverter side and the optimal secondary winding current on the rectifier side. The system parameters include the eddy current loss components corresponding to the primary winding, the eddy current loss components corresponding to the secondary winding, the parasitic resistance of the primary winding, the equivalent resistance on the inverter side, the parasitic resistance of the secondary winding, the equivalent resistance on the rectifier side, the electric field strength generated by the primary winding, the electric field strength generated by the secondary winding, and the seawater conductivity.

[0031] It should be noted that the identified mutual inductance includes the first mutual inductance identified in step S100, which corresponds to the first mutual inductance after step S100 is executed; and the second mutual inductance identified in step S500, which corresponds to the second mutual inductance after step S600 returns to this step.

[0032] In acquiring mutual intuition M and output power P o After obtaining the system parameters, this embodiment establishes a total system loss model and determines the optimal transmission current with the goal of minimizing total loss. Total Loss P loss (See formula (12)) with the emission current I tx The change has a unique global minimum, and the corresponding system operating point is the optimal operating point. Based on this, the optimal primary coil current... The following formula is used to obtain: (2); in, X 1 represents the intermediate variable corresponding to the internal resistance of the primary coil and the internal resistance of the inverter side. X 2 represents the intermediate variables corresponding to the internal resistance of the secondary coil and the internal resistance of the rectifier side. E 1 represents the eddy current loss component corresponding to the primary coil. F It is an intermediate variable for the eddy current loss component corresponding to the secondary coil. Specifically, (2-1) (2-2) (2-3) (2-4) (2-5); Among them, R tx R is the parasitic resistance of the primary coil. f_tx R is the equivalent resistance on the inverter side. rx R is the parasitic resistance of the secondary coil. f_rx Y1 is the equivalent resistance of the rectifier side, Y2 is the electric field strength generated by the primary coil, Y2 is the electric field strength generated by the secondary coil, and σ is the conductivity of seawater. Once the system is determined, these parameters can be calculated. V is the volume of the primary and secondary coils facing each other, and E2 is the eddy current loss component corresponding to the secondary coil.

[0033] Furthermore, the optimal secondary coil current The following formula is used to obtain: (3); in, This refers to the output power.

[0034] Under the condition that the system operates at the resonant frequency to reduce reactive power, the output power satisfies: (4); in, Let be the turns ratio of the transformer in the i-th inverter unit on the inverter side; Let be the turns ratio of the transformer in the j-th rectifier unit on the rectifier side. In a specific embodiment, each Equal, each equal.

[0035] P ref The basic unit characterizing the power transmission capability of this multi-converter wireless power transfer system is expressed as follows: (5); in, This is the input voltage on the inverter side. This is the output voltage on the rectifier side. Based on the above embodiments, the mechanism by which this method achieves high-power wide-range adjustment is mainly reflected in two aspects: on the one hand, P o The output power is related to the control quantities of each inverter and rectifier unit. Therefore, by increasing the number of conversion units, the transmission power level of the system can be directly improved, enabling high-power expansion for underwater intelligent equipment. On the other hand, the output power depends not only on the number of modules but also on the phase shift angle of each unit. α i and duty cycle D jTherefore, with a given number of modules, continuous power regulation can still be achieved by adjusting control variables. In other words, this method has the ability to both expand discrete power by increasing the number of units and achieve continuous power regulation by adjusting key control quantities, thus balancing the needs of high power transmission and wide-range regulation.

[0036] S300. Calculate the phase shift angle of the first inverter unit and the duty cycle of the first rectifier unit based on the optimal primary coil current and the optimal secondary coil current.

[0037] Since the auxiliary modules (the remaining inverter units and rectifier units mentioned above) operate with fixed control values, the equivalent excitation voltage on the inverter side is... V inv Equivalent rectified voltage on the rectifier side V rec They can be simplified as follows: (6); (7); Then the phase shift angle of the first inverter module can be calculated. α 1 and the duty cycle of the first rectifier module D 1: (8); (9); in, For the above The corresponding rectifier-side voltage.

[0038] Optimal current I tx_op and I rx_op After substituting, the optimal phase shift angle can be obtained. α 1_op and optimal duty cycle D 1_op Furthermore, the phase shift angle of the first inverter unit... Duty cycle of the first rectifier unit The mathematical expressions are as follows: (10); (11); in, Input voltage, This represents the number of inverter units. This refers to the turns ratio of the inverter-side transformer. For output voltage, The number of rectifier units. This represents the turns ratio of the rectifier-side transformer.

[0039] S400: Based on the relationship between the sampled output current and output voltage and the set reference output current and reference output voltage, fine-tune the calculated phase shift angle and duty cycle.

[0040] In a specific embodiment, step S400 includes the following steps: Based on the sampled output current and voltage, as well as the reference output current and voltage, determine whether the entire system is in constant current mode or constant voltage mode. Specifically, if the output current equals the reference output current, the system is in constant current mode; if the output voltage equals the reference output voltage, the system is in constant voltage mode.

[0041] When in constant current mode, if the output current is less than the reference output current, the phase shift angle and duty cycle are increased slightly according to the set parameters; if the output current is greater than the reference output current, the phase shift angle and duty cycle are decreased slightly according to the set parameters. When in constant voltage mode, if the output voltage is less than the reference output voltage, the calculated phase shift angle and duty cycle are increased slightly according to the set parameters; if the output voltage is greater than the reference output voltage, the calculated phase shift angle and duty cycle are decreased slightly according to the set parameters.

[0042] In practical implementation, a slight increase in phase shift angle Δ is set. α 1 = 0.1, increasing the duty cycle by a small amount Δ D 1 = 0.001; Set to reduce the phase shift angle by a small amount Δ α 1 = -0.1, setting a slight reduction in duty cycle Δ D 1 = -0.001.

[0043] The phase shift angle of the updated first inverter unit is The updated duty cycle of the first rectifier unit is .

[0044] To make it easier to understand, a small increment Δ is introduced based on the theoretical optimum. α 1 and Δ D 1. Fine-tuning is performed so that the system can gradually approach the actual optimal operating point and maintain high-efficiency constant current / constant voltage charging operation even when parameter drift, temperature rise changes and measurement errors exist.

[0045] S500 samples the output current, output voltage, and rectified side current to identify the second mutual inductor and the second load.

[0046] This step is to determine whether the mutual inductance and load have changed when the system is working. If they have changed, it is necessary to return to step S200 to reset the initial phase shift angle and duty cycle of the system.

[0047] S600: If the second mutual inductance is not equal to the first mutual inductance or the second load is not equal to the first load, return to step S200; if the second mutual inductance is equal to the first mutual inductance and the second load is equal to the first load, determine whether the output current and output voltage have reached the set values. If so, maintain the current state of efficient charging; otherwise, return to step S400.

[0048] In one or more embodiments, the total system loss includes power device conduction losses, coil losses, rectification losses, and resonant inductor-integrated transformer losses. Specifically, Total system loss Including circuit losses P cir and seawater eddy current loss P eddy Therefore, it can be represented as: (12); in, The primary coil current is... This is part of the eddy current loss. This refers to the transformer core loss.

[0049] The circuit losses include power device conduction losses, coil losses, rectification losses, and resonant inductor-transformer losses. From the above equation, it can be seen that the total system loss has a unique minimum as the transmitting current changes; therefore, the optimal primary coil current can be obtained. I tx_op and the optimal secondary coil current I rx_op .

[0050] The corresponding minimum total loss is: (13); To make it easier to understand, for a given system, the first thing to do is to calculate the system’s losses. From this loss expression, we can see that the total loss is a function of the primary coil current Itx, and it is a U-shaped function with a global minimum.

[0051] In summary, this embodiment applies optimal control parameters to the first inverter unit and the first rectifier unit, while the remaining auxiliary conversion units maintain preset fixed operating states, thereby bringing the system close to the theoretical optimal efficiency point. Simultaneously, through mutual inductance identification, load calculation, and total loss optimization, the control quantities of key conversion units are jointly adjusted, achieving wide-range power transmission while ensuring high-efficiency operation and constant-current / constant-voltage charging control, demonstrating significant engineering application value.

[0052] Example 2: Figure 2 , Figure 3As shown, the present invention also provides a multi-converter underwater wireless power transfer system based on optimal current control, including a first inverter unit and a first rectifier unit as described in the efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control in Embodiment 1, and other inverter units and other rectifier units; the first inverter unit and other inverter units are connected in parallel, with their parallel input terminals connected to an input power supply, and the first rectifier unit and other rectifier units are connected in parallel, with their parallel output terminals serving as an output power supply for connecting underwater intelligent equipment; the first inverter unit and other inverter units constitute the inverter side, and the first rectifier unit and other rectifier units constitute the rectifier side.

[0053] Furthermore, it also includes a transformer disposed between the inverter side and the rectifier side, a base station-side resonant compensation network integrated in the primary transmitting coil of the transformer, an equipment-side resonant compensation network integrated in the secondary receiving coil of the transformer, the output terminals of the first inverter unit and the remaining inverter units being connected to the base station-side resonant compensation network, and the input terminals of the first rectifier unit and the remaining rectifier units being connected to the equipment-side resonant compensation network.

[0054] In one or more embodiments, the first inverter unit includes a capacitor C1, field-effect transistors S11, S21, S31, and S41; one plate of capacitor C1, the drain of field-effect transistor S11, and the drain of field-effect transistor S21 are all connected to one terminal of the input power supply, and the other plate of capacitor C1, the source of field-effect transistor S31, and the source of field-effect transistor S41 are all connected to the other terminal of the input power supply, the source of field-effect transistor S11 and the drain of field-effect transistor S31 are connected together, and the source of field-effect transistor S21 and the drain of field-effect transistor S41 are connected together.

[0055] The base station-side resonance compensation network includes capacitor C. f_ga Capacitor C ga Capacitor C f_ga One plate, capacitor C ga One of the plates is connected to the emitter coil L. ga At both ends, capacitor C f_ga The other plate, capacitor C ga The other plate is connected to the source of the field-effect transistor S11 and the drain of the field-effect transistor S31.

[0056] The remaining inverse conversion units are all DC-AC inverters. The positive and negative input terminals of each DC-AC inverter are connected to the positive and negative terminals of the input power supply, respectively. The output terminal of each DC-AC inverter is connected to the two ends of the primary winding of a transformer. The secondary windings of the transformer connected to each DC-AC inverter are connected in series. One end of the series connection is connected between MOSFETs S21 and S41, and the other end is connected to the emitter coil L. ga Capacitor C f_gaBetween. Among them, the turns ratio of the primary and secondary windings of the transformer corresponding to inverter unit #2 is m. p12 :m p22 The turns ratio of the primary and secondary windings of the transformer corresponding to the #m inverter unit is m. p1m :m p2m .

[0057] The first rectifier unit includes a field-effect transistor Q11, a field-effect transistor Q21, a diode D11, and a diode D21. The source of field-effect transistor Q11 and the source of field-effect transistor Q21 are connected to the positive terminal of the electronic load, and the negative terminals of diodes D11 and D21 are connected to the negative terminal of the electronic load.

[0058] The equipment-side resonant compensation network includes capacitor C. f_va Capacitor C va Capacitor C f_va One plate, capacitor C va One of the plates is connected to the receiving coil L. va At both ends, capacitor C f_va The other plate, capacitor C va The other plate is connected to the drain of the field-effect transistor Q11 and the positive terminal of the diode D11.

[0059] The remaining rectifier units are all AC-DC rectifiers. The positive output terminal of each AC-DC rectifier is connected to the positive terminal of the electronic load, and the negative output terminal of each AC-DC rectifier is connected to the negative terminal of the electronic load. The input terminals of each AC-DC rectifier are connected to the primary winding of a transformer. The secondary windings of the transformer connected to each AC-DC rectifier are connected in series. One end of the series connection is connected between the field-effect transistor Q21 and the diode D21, and the other end is connected to the capacitor C. f_va Receiver coil L va Between. Among them, the turns ratio of the secondary primary winding of the transformer corresponding to rectifier unit #2 is n. s22 :n s12 The turns ratio of the secondary primary winding of the transformer corresponding to the inverter unit is n. s2n :n s1n .

[0060] The aforementioned multiple inverter units, base station-side resonant compensation network, and transmitting coil constitute the charging base station, while the receiving coil, equipment-side resonant compensation network, and multiple rectifier units constitute the underwater intelligent equipment end. Both the base station and equipment sides employ LCC resonant compensation networks to improve the system's design flexibility and transmission capacity under high-power operating conditions. Some units in each inverter and rectifier unit are connected to the AC power transmission circuit via a resonant inductor integrated transformer. The leakage inductance of the resonant inductor integrated transformer is reused as a resonant inductor, thereby reducing the need for additional resonant inductor devices and decreasing system size and cost. This structure allows for modular expansion of the system's power levels and adapts to energy transmission requirements under different coupling states, output power, and load conditions.

[0061] It should be noted that the system in this embodiment, through the efficiency optimization method of the multi-converter underwater wireless power transfer system based on optimal current control in Embodiment 1, can ensure that the system output meets the constant voltage or constant current charging requirements, while achieving wide-range power transfer and high-efficiency operation.

[0062] The above description is merely a preferred embodiment of the present invention. Those skilled in the art will understand that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. An efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control, characterized in that, In the multi-converter underwater wireless power transmission system, except for the first inverter unit and the first rectifier unit, the phase shift angles of the remaining inverter units are fixed, and the duty cycles of the remaining rectifier units are fixed. The method includes: S100: Identify the first mutual inductor and the first load by sampling the output current, output voltage and rectifier side current; S200. Based on the identified mutual inductance, output power, and system parameters, calculate the optimal primary winding current on the inverter side and the optimal secondary winding current on the rectifier side. S300. Calculate the phase shift angle of the first inverter unit and the duty cycle of the first rectifier unit based on the optimal primary coil current and the optimal secondary coil current. S400. Based on the relationship between the sampled output current and output voltage and the set reference output current and reference output voltage, fine-tune the calculated phase shift angle and duty cycle. S500: Sample output current, output voltage and rectified side current to identify the second mutual inductor and the second load; S600: If the second mutual inductance is not equal to the first mutual inductance or the second load is not equal to the first load, return to step S200; if the second mutual inductance is equal to the first mutual inductance and the second load is equal to the first load, determine whether the output current and the output voltage have reached the set values. If so, maintain the current state of efficient charging; otherwise, return to step S400.

2. The efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control according to claim 1, characterized in that, Step S400 includes the following steps: Based on the sampled output current and output voltage, as well as the reference output current and reference output voltage, determine whether the entire system is in constant current mode or constant voltage mode; When in constant current mode, if the output current is less than the reference output current, the phase shift angle and duty cycle are calculated and increased by a set small amount. If the output current is greater than the reference output current, the phase angle and duty cycle are calculated according to the set slight reduction; When in the constant voltage mode, if the output voltage is less than the reference output voltage, the phase shift angle and duty cycle are increased by a set small amount. If the output voltage is greater than the reference output voltage, the phase shift angle and duty cycle are calculated by slightly reducing the set value.

3. The efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control according to claim 1, characterized in that, Mutual inductance between inverter side and rectifier side Identified by the following expression: ； in, ω The system's operating angular frequency, This is the sum of the leakage inductance of the inverter-side transformer. This is the sum of the leakage inductance of the rectifier-side transformer. This is the inverter-side voltage. This is the rectifier-side current.

4. The efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control according to claim 3, characterized in that, The optimal primary coil current The following formula is used to obtain: ， in, X 1 represents the intermediate variable corresponding to the internal resistance of the primary coil and the internal resistance of the inverter side. X 2 represents the intermediate variables corresponding to the internal resistance of the secondary coil and the internal resistance of the rectifier side. E 1 represents the eddy current loss component corresponding to the primary coil. F It is an intermediate variable for the eddy current loss component corresponding to the secondary coil.

5. The efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control according to claim 4, characterized in that, The optimal secondary coil current The following formula is used to obtain: ； in, This refers to the output power.

6. The efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control according to claim 5, characterized in that, Calculate the phase shift angle of the first inverter unit. Duty cycle of the first rectifier unit The mathematical expressions are as follows: ； ； in, Input voltage, This represents the number of inverter units. This refers to the turns ratio of the inverter-side transformer. For output voltage, The number of rectifier units. This represents the turns ratio of the rectifier-side transformer.

7. The efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control according to claim 1, characterized in that, The first load and the second load are identified by corresponding sampled output current and output voltage.

8. The efficiency optimization method for a multi-converter underwater wireless power transfer system based on optimal current control according to claim 7, characterized in that, It also includes establishing a total system loss model after obtaining mutual inductance and output power, and determining the optimal transmission current with the goal of minimizing the total system loss; The total system loss includes circuit loss and seawater eddy current loss; the circuit loss includes power device conduction loss, coil loss, rectification loss, and resonant inductor integrated transformer loss.

9. A multi-converter underwater wireless power transfer system based on optimal current control, characterized in that, The system includes the first inverter unit and the first rectifier unit, as well as the remaining inverter units and the remaining rectifier units, as described in any one of claims 1-8, in the method for optimizing the efficiency of a multi-converter underwater wireless power transfer system based on optimal current control. The first inverter unit and the remaining inverter units are connected in parallel, with their input terminals connected to an input power supply. The first rectifier unit and the remaining rectifier units are also connected in parallel, with their output terminals connected to an electronic load. The first inverter unit and the remaining inverter units constitute the inverter side, and the first rectifier unit and the remaining rectifier units constitute the rectifier side. It also includes a transformer disposed between the inverter side and the rectifier side, a base station-side resonant compensation network integrated into the primary side transmitting coil of the transformer, an equipment-side resonant compensation network integrated into the secondary side receiving coil of the transformer, the output terminals of the first inverter unit and the remaining inverter units being connected to the base station-side resonant compensation network, and the input terminals of the first rectifier unit and the remaining rectifier units being connected to the equipment-side resonant compensation network.

10. A multi-converter underwater wireless power transfer system based on optimal current control according to claim 9, characterized in that, The first inverter unit includes a capacitor C1, a field-effect transistor (FET) S11, a field-effect transistor (FET) S21, a field-effect transistor (FET) S31, and a field-effect transistor (FET) S41. One plate of capacitor C1, the drain of FET S11, and the drain of FET S21 are all connected to one terminal of the input power supply. The other plate of capacitor C1, the source of FET S31, and the source of FET S41 are all connected to the other terminal of the input power supply. The source of FET S11 and the drain of FET S31 are connected together, and the source of FET S21 and the drain of FET S41 are connected together. The base station-side resonance compensation network includes capacitor C. f_ga Capacitor C ga Capacitor C f_ga One plate, capacitor C ga One of the plates is connected to the emitter coil L. ga At both ends, capacitor C f_ga The other plate, capacitor C ga The other plate is connected to the source of the field-effect transistor S11 and the drain of the field-effect transistor S31; The remaining inverse conversion units are all DC-AC inverters. The positive and negative input terminals of each DC-AC inverter are connected to the positive and negative terminals of the input power supply, respectively. The output terminal of each DC-AC inverter is connected to the two ends of the primary winding of a transformer. The secondary windings of the transformer connected to each DC-AC inverter are connected in series. One end of the series connection is connected between MOSFETs S21 and S41, and the other end is connected to the emitter coil L. ga Capacitor C f_ga between; The first rectifier unit includes a field-effect transistor Q11, a field-effect transistor Q21, a diode D11, and a diode D21. The source of field-effect transistor Q11 and the source of field-effect transistor Q21 are connected to the positive terminal of the electronic load, and the negative terminals of diode D11 and the negative terminal of diode D21 are connected to the negative terminal of the electronic load. The equipment-side resonance compensation network includes capacitor C. f_va Capacitor C va Capacitor C f_va One plate, capacitor C va One of the plates is connected to the receiving coil L. va At both ends, capacitor C f_va The other plate, capacitor C va The other plate is connected to the drain of the field-effect transistor Q11 and the positive terminal of the diode D11; The remaining rectifier units are all AC-DC rectifiers. The positive output terminal of each AC-DC rectifier is connected to the positive terminal of the electronic load, and the negative output terminal of each AC-DC rectifier is connected to the negative terminal of the electronic load. The input terminals of each AC-DC rectifier are respectively connected to the two ends of the primary winding of a transformer. The secondary windings of the transformer to which each AC-DC rectifier is connected are connected in series. One end of the series connection is connected between the field-effect transistor Q21 and the diode D21, and the other end of the series connection is connected to the capacitor C. f_va Receiver coil L va between.

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