Underwater parallel transmission system based on magnetic field and electric field for transmitting electric energy and signal respectively

Abstract

The application relates to the technical field of wireless power and signal parallel transmission, and particularly discloses an underwater parallel transmission system based on magnetic field and electric field for transmitting power and signals respectively, which establishes a coupling mechanism model of energy and signals, gives a design method of the energy coupling mechanism, proposes an embedded coupling mechanism structure, establishes an underwater energy loop topology (LCC-S resonance topology) based on the theory of a magnetic coupled wireless power transfer (MC-WPT) system, establishes an underwater signal loop topology based on the theory of an electric-field coupled wireless power transfer (EC-WPT) system, and gives a system parameter design method. The system realizes parallel transmission of energy and signals, realizes bidirectional high-speed transmission of signals, and realizes almost no energy interference to signals without affecting the transmission of power.

Description

Technical Field

[0001] This invention relates to the field of parallel wireless power and signal transmission technology, and in particular to an underwater parallel transmission system based on magnetic fields and electric fields for transmitting electrical power and signals respectively. Background Technology

[0002] Wireless power transmission has many advantages over traditional wired transmission, such as convenience, aesthetics, and safety. Especially in special environments such as dusty or underwater environments, plug-and-play power supply methods are prone to generating electric arcs, which can lead to explosions in dusty environments, and exposed plugs can leak electricity underwater. Watertight plugs, on the other hand, have complex structures and are expensive.

[0003] Underwater wireless power supply offers significant advantages over plug-and-play power supply, leading to its increasing research and application in underwater equipment. Most devices require data exchange with the power source while simultaneously drawing power. However, traditional wireless communication methods like WiFi rely heavily on electromagnetic waves, which attenuate severely underwater, making data transmission difficult. Furthermore, electromagnetic wave transmission lacks directionality and offers poor security. Against this backdrop, Simultaneous Wireless Power and Data Transfer (SWPDT) technology has emerged. Current underwater SWPDT technologies almost exclusively utilize either magnetic coupling or electric field coupling. Shared-channel SWPDT systems typically require complex topologies to reduce crosstalk between energy and signal; separate-channel SWPDT systems often require specially designed coupling mechanisms or additional circuit components to address cross-coupling issues. The cross-coupling problem in a split-channel SWPDT system is mainly due to the fact that energy and signal use the same coupling method. Summary of the Invention

[0004] This invention provides an underwater parallel transmission system based on magnetic and electric fields for transmitting electrical energy and signals respectively. The technical problem it solves is how to solve the cross-coupling problem of energy and signal in existing separate channel SWPDT systems without designing special coupling mechanism shapes or adding additional circuit components.

[0005] To address the above technical problems, this invention provides an underwater parallel transmission system based on magnetic and electric fields for transmitting electrical energy and signals respectively. The system includes a coupling mechanism comprising a symmetrically arranged primary structure and a secondary structure. The primary structure includes a primary metal shield, a primary coil, and a primary external metal plate disposed in the hollow region of the primary coil, arranged in layers. The secondary structure includes a secondary metal shield, a secondary coil, and a secondary external metal plate disposed in the hollow region of the secondary coil, arranged in layers. The primary coil and the secondary coil are magnetically coupled to transmit electrical energy, and the primary metal shield, the primary external metal plate, the secondary metal shield, and the secondary external metal plate are electrically coupled to transmit signals.

[0006] Preferably, both the primary coil and the secondary coil are circular coils with an outer diameter of d. o The inner diameter is d i The wire diameter is c r The design steps for the parameters of the primary coil and the secondary coil, with a number of turns of N, are as follows:

[0007] E1. Determine the system output voltage U based on system requirements. out System output power P out , electrical energy transmission distance d, outer diameter d of the circular coil o ;

[0008] E2, according to U out P out Calculate the current in the primary coil, which is also the current in the secondary coil.

[0009] E3. According to the Litz wire selection manual provided by the manufacturer and the current I... c , power transmission frequency f e Determine the wire diameter c r ;

[0010] E4. According to wire diameter c r Determine the inner diameter d i According to the outer diameter d o Inner diameter d i wire diameter c r Determine the number of coil turns

[0011]

[0012] E5. According to wire diameter c r Outer diameter d o Inner diameter d i The self-inductance L of the primary coil is obtained from the number of turns N and the power transmission distance d. p The self-inductance L of the secondary coil sAnd the mutual inductance M between the primary coil and the secondary coil wa .

[0013] Preferably, both the primary metal shielding plate and the secondary metal shielding plate have a side length of d. o The square electrode plate, wherein both the primary external metal plate and the secondary external metal plate have a side length of l. a Square electrode plates.

[0014] Preferably, the system further includes a DC power supply, a high-frequency inverter, a primary compensation network, a secondary compensation network, a rectifier and filter circuit, and a load, wherein the primary compensation network is connected to the primary coil, and the secondary compensation network is connected to the secondary coil.

[0015] The primary compensation network adopts an LCC resonant network, specifically including a series resonant inductor L. r Primary series resonant capacitor C p and parallel resonant capacitor C r ;

[0016] The secondary compensation network adopts an S-type compensation network, including a secondary series resonant capacitor C. s .

[0017] Preferably, the system also includes a primary signal transmitting and receiving module and a primary signal detection resistor R connected thereto. b1 and the connected secondary signal detection resistor R b2 Secondary signal transmitting and receiving module; the primary signal detection resistor R b1 The two ends are respectively connected to the primary metal shielding plate and the primary external metal plate, and the secondary signal detection resistor R b2 The two ends are respectively connected to the secondary metal shielding plate and the secondary external metal plate, and R has b1 =R b2 =R b .

[0018] Preferably, the system parameters are designed using the following steps:

[0019] S1. Determine the system output voltage U based on system requirements. out System output power P out Energy circuit operating frequency f e , electrical energy transmission distance d, outer diameter d of the circular coil o DC input voltage U dc ;

[0020] S2, determine L using steps E2 to E5. p L s And the mutual inductance M between the primary and secondary coils, i.e., M wa; Calculate the coupling capacitance C between the primary and secondary metal shielding plates based on the determined primary and secondary metal shielding plates. 12 ;

[0021] S3, according to M, U out U dc Calculate the series resonant inductance L r ; Calculate C based on the resonance relationship r C p C s According to the inner diameter d of the circular coil i Determine the side length l of the primary and secondary external metal plates. a ; Calculate the coupling capacitance C between the primary and secondary external metal plates based on the determined metal plates. 34 Self-containment C between primary metal plates 13 Self-containment C between secondary metal plates 24 The cross-coupling capacitance C between the primary and secondary metal plates 14 C 23 ;

[0022] S4. Determine if the output voltage reaches the target voltage; otherwise, decrease L. r Then re-evaluate; if yes, proceed to the next step; re-measure the mutual inductance M between the primary and secondary coils and determine whether the rate of change of mutual inductance ΔM is less than the set margin; if yes, proceed according to R... b Determining the effect curve on signal transmission R b If the value is not specified, proceed to the next step; otherwise, decrease l. a And recalculate C 34 C 13 C 24 C 14 C 23 Then reassess;

[0023] S5. Parameter design is complete; output L at this point. r l a .

[0024] Preferably, in step S3, according to the formula Calculate L r ;

[0025] C is calculated according to the following formula. 12 C 34 C 13 C 24 C 14 C 23 Any capacitance value C in:

[0026]

[0027] Where ε is the dielectric constant of the freshwater environment, a is the width of the directly opposite portion of the plates, b is the length of the directly opposite portion of the plates, and d is the distance between the directly opposite portions of the plates.

[0028] Preferably, in step S4, according to R b Determining the effect curve on signal transmission R b The value is specifically: select one that can achieve 95% G. smax R b Value, G smax This indicates the maximum gain of the signal transmission.

[0029] Preferred, C 13 C 24 C 14 C 23 satisfy:

[0030]

[0031] G smax Calculated by the following formula:

[0032]

[0033] in, All are equivalent capacitances.

[0034] Preferably, the primary signal transmitting and receiving module includes a primary signal transmitting circuit, a primary signal receiving circuit, and a primary switching circuit, and the secondary signal transmitting and receiving module includes a secondary signal transmitting circuit, a secondary signal receiving circuit, and a secondary switching circuit.

[0035] The primary switching circuit controls the primary signal transmitting circuit to connect the primary signal detection resistor R. b1 During signal transmission, the secondary switching circuit controls the secondary signal receiving circuit to connect the secondary signal detection resistor R. b2 It performs signal reception, enabling forward signal transmission from primary to secondary.

[0036] The secondary switching circuit controls the secondary signal transmitting circuit to connect the secondary signal detection resistor R. b2 To transmit a signal, the primary switching circuit controls the primary signal receiving circuit to connect the primary signal detection resistor R. b1 It receives signals and enables reverse transmission of signals from the secondary to the primary stage.

[0037] This invention provides an underwater parallel transmission system based on magnetic and electric fields for transmitting electrical energy and signals respectively. It establishes a coupling mechanism model for energy and signals, presents a design method for the energy coupling mechanism, proposes an embedded coupling mechanism structure, establishes an underwater energy loop topology (using an LCC-S resonant topology) based on the theory of magnetically coupled wireless power transfer (MC-WPT) systems, and establishes an underwater signal loop topology based on the theory of electric-field coupled wireless power transfer (EC-WPT) systems. The system parameter design method is also provided. This system achieves parallel transmission of energy and signals, realizes bidirectional high-speed signal transmission, and achieves virtually no energy interference with the signal without affecting the transmission of electrical energy. Attached Figure Description

[0038] Figure 1 This is a diagram illustrating the operating mechanism and composition of an underwater parallel transmission system based on magnetic and electric fields for transmitting electrical energy and signals, respectively, according to an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of signal modulation and transmission provided in an embodiment of the present invention, wherein (a) is a schematic diagram of the signal modulation and transmission terminal TX2, and (b) is an equivalent model of the TX2 terminal;

[0040] Figure 3 This is a schematic diagram of the signal receiving and demodulation terminal provided in an embodiment of the present invention, wherein (a) and (b) are schematic diagrams of the signal modulation receiving terminals TX1 and TX2, respectively;

[0041] Figure 4 This is an equivalent model diagram of underwater eddy current loss provided in an embodiment of the present invention;

[0042] Figure 5 This is an equivalent model diagram of the underwater environment MC-WPT system provided in the embodiments of the present invention;

[0043] Figure 6 This is a design flowchart of the energy coupling mechanism provided in an embodiment of the present invention;

[0044] Figure 7 This is a model diagram of the signal coupling mechanism provided in an embodiment of the present invention;

[0045] Figure 8 This is a schematic diagram of the embedded coupling mechanism structure provided in an embodiment of the present invention;

[0046] Figure 9This is a schematic diagram of the direction of induced current generated in a metal plate under different states provided in the embodiments of the present invention, wherein (a) and (b) correspond to the states without an external closed loop and the states with an external closed loop, respectively;

[0047] Figure 10 This is a cross-sectional view of the magnetic flux model of the coupling mechanism provided in the embodiment of the present invention;

[0048] Figure 11 This is a diagram of a 15-capacitor coupling model provided in an embodiment of the present invention;

[0049] Figure 12 This is the equivalent circuit diagram of the LCC-S compensation topology provided in the embodiments of the present invention;

[0050] Figure 13 This is a diagram of a six-capacitor coupling model provided in an embodiment of the present invention;

[0051] Figure 14 This is the π-type equivalent circuit diagram of the signal loop provided in the embodiment of the present invention;

[0052] Figure 15 The signal output resistance R provided in this embodiment of the invention is at different frequencies. b With signal gain G s Relationship diagram;

[0053] Figure 16 This is a parameter design flowchart provided in an embodiment of the present invention;

[0054] Figure 17 The external metal plate with side length l provided in this embodiment of the invention a With the self-inductance L of the primary coil p And the relationship diagram of mutual inductance M between coils;

[0055] Figure 18 This is a Simulink simulation model diagram of the energy loop provided in an embodiment of the present invention;

[0056] Figure 19 This is a waveform diagram of the inverter voltage and inverter current in steady state provided by an embodiment of the present invention;

[0057] Figure 20 This is a waveform diagram of load voltage and load current provided in an embodiment of the present invention;

[0058] Figure 21 This is a Simulink simulation model diagram of the signal loop provided in an embodiment of the present invention;

[0059] Figure 22 These are waveform diagrams of the input and output signals provided in the embodiments of the present invention, wherein (a) and (b) correspond to the forward and reverse transmission of the signals, respectively;

[0060] Figure 23 These are voltage waveforms across the input and output resistors provided in this embodiment of the invention, where (a) and (b) correspond to forward and reverse signal transmission, respectively.

[0061] Figure 24 This is a diagram showing the interference effect of energy on signals via magnetic field coupling, as provided in an embodiment of the present invention.

[0062] Figure 25 This is a diagram showing the interference effect of energy on signals via electric field coupling, as provided in an embodiment of the present invention. Detailed Implementation

[0063] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0064] This invention provides an underwater parallel transmission system based on magnetic and electric fields for transmitting electrical energy and signals respectively, such as... Figure 1 As shown, the energy signal synchronous transmission method used in this embodiment is a separate channel type. Therefore, in terms of structure, the energy and signal channels are independent of each other, which can avoid crosstalk between energy and signal through direct connection loop.

[0065] The energy channel mainly consists of a DC power supply, a high-frequency inverter, a primary compensation network, an energy coupling coil, a secondary compensation network, a rectifier and filter circuit, and a load. Its operating mechanism is as follows: First, a stable DC voltage is generated by the DC source. Then, a drive signal drives the switching elements of the high-frequency inverter, enabling the inverter to convert the DC voltage into a high-frequency AC voltage. This AC voltage is then injected into the primary resonant network and subsequently into the coupling coil. In the energy coupling coil, energy is conducted from the primary coil to the secondary coil through electromagnetic induction. After passing through the secondary compensation network, the high-frequency AC voltage is transmitted to the front end of the rectifier circuit. The rectifier circuit converts this AC voltage into a DC voltage, which, after filtering, becomes a nearly constant DC voltage supplied to the load.

[0066] The signal channel has a relatively simple structure, consisting of modulation and demodulation modules on both sides of the channel, detection resistors, and coupling capacitor plates. Specifically, the signal channel includes a primary signal transmitting and receiving module and a primary signal detection resistor R. b1 and the connected secondary signal detection resistor R b2 The primary signal detection resistor R is a secondary signal transmitting and receiving module. b1 The two ends are connected to the primary metal shield and the primary external metal plate, respectively, and the secondary signal detection resistor Rb2 The two ends are respectively connected to the secondary metal shielding plate and the secondary external metal plate. The primary signal transmitting and receiving module includes a primary signal transmitting circuit, a primary signal receiving circuit, and a primary switching circuit. The secondary signal transmitting and receiving module includes a secondary signal transmitting circuit, a secondary signal receiving circuit, and a secondary switching circuit. The primary switching circuit controls the primary signal transmitting circuit to connect the primary signal detection resistor R. b1 Signal transmission is performed, and the secondary switching circuit controls the secondary signal receiving circuit to connect the secondary signal detection resistor R. b2 Signal reception is performed to achieve forward signal transmission from the primary to the secondary stage; the secondary switching circuit controls the secondary signal transmitting circuit to connect the secondary signal detection resistor R. b2 To transmit a signal, the primary switching circuit controls the primary signal receiving circuit to connect the primary signal detection resistor R. b1 It receives signals and enables reverse transmission of signals from the secondary to the primary stage.

[0067] The signal is modulated by a modem module, injected into both ends of the detection resistor, and then transmitted through capacitive coupling plates via displacement current between the capacitors to both ends of the other detection resistor. There, the modem module connected in parallel picks up and demodulates the signal. This embodiment uses an OFDM modem module, and the signal loop in this embodiment has a symmetrical structure, which in principle enables bidirectional communication.

[0068] As can be seen from the above description, the energy channel and signal channel use independent coupling mechanisms and different transmission principles, thus requiring a specific structure to combine these two coupling mechanisms. Figure 1 As shown in the schematic diagram of the coupling mechanism, the energy channel uses a circular coil for transmission, and the signal channel uses two pairs of square metal plates for transmission. One pair consists of large metal plates that shield radiation in the magnetic field coupling mechanism, which are reused as signal transmission plates in this embodiment; the other pair consists of external metal plates that form another pair of capacitor plates for signal transmission.

[0069] Therefore, the coupling mechanism of this system specifically includes a symmetrically arranged primary structure and a secondary structure. The primary structure includes a primary metal shield plate, a primary coil, and a primary external metal plate arranged in layers within the hollow region of the primary coil. The secondary structure includes a secondary metal shield plate, a secondary coil, and a secondary external metal plate arranged in layers within the hollow region of the secondary coil. The primary coil and the secondary coil are magnetically coupled to transmit electrical energy, and the primary metal shield plate, the primary external metal plate, the secondary metal shield plate, and the secondary external metal plate are electric field coupled to transmit signals.

[0070] Half-bridge inverters have low utilization of power supply voltage, with the output being only half of the input voltage; the inductance of push-pull circuits will increase weight and size to some extent, and the switching transistors will bear voltage stress twice that of DC voltage. Therefore, this embodiment believes that using a full-bridge inverter circuit is more suitable.

[0071] The LCC-S features constant voltage output and is insensitive to changes in primary-side parameters. Secondary-side compensation still uses series compensation, without increasing the weight, size, or complexity of the secondary side. Adjusting the series compensation inductor L... r The value of LCC-S can be used to adjust the ratio of DC input voltage to load output voltage, which greatly reduces the difficulty of parameter design. Therefore, this embodiment uses LCC-S as the energy channel resonant network.

[0072] In the transmission of digital signals, they need to be modulated according to certain methods to transmit as modulated waves in the channel. Based on the waveform characteristics of the carrier medium used in digital modulation, it can be divided into single-carrier modulation, multi-carrier modulation, and pulse modulation. Traditional modulation methods are mostly single-carrier modulation, which is equivalent to serial signal transmission and is often limited in speed. Multi-carrier modulation technology emerged and has developed to its current state based on single-carrier modulation technology. Multi-carrier technology separates the serial signal onto multiple frequency subcarriers, allowing the originally serially transmitted signal to be transmitted in parallel. For frequency-selective interference, multiple frequency carriers can reduce interference, and for channels with a tolerant frequency range, it can significantly improve transmission speed. Orthogonal Frequency Division Multiplexing (OFDM) modulation technology is one of the most popular and widely used multi-carrier modulation technologies today.

[0073] The forward and reverse signal transmission uses OFDM modulation technology. OFDM modulation technology is a type of multi-carrier modulation. Its principle is to use serial-to-parallel conversion to transform the high-speed serial data stream into a separate low-speed data stream and modulate it on the subcarrier, which can meet the requirements of high-speed data transmission. Figure 2 This is a schematic diagram of signal modulation and transmission provided in an embodiment of the present invention. Figure 2 In (a), u sig2 For rectangular digital signals, the modulation and demodulation chip used in the modulation circuit is the QCA6410. During signal transmission, the QCA6410 chip performs OFDM modulation on the input data, and after D / A conversion and power amplification, it outputs the signal to the OUT terminal of the modulation circuit. The signal is then injected into the main circuit through a high-frequency isolation transformer. From the g and f terminals, the signal modulation and transmitting circuit TX2 can be equivalent to a voltage source u. s2 Therefore, the signal modulation and transmitting circuit TX2 can be approximated as follows: Figure 2 (b) shows the voltage source.

[0074] Signal demodulation refers to the process of restoring a modulated carrier wave to a digital signal. Figure 3 This is a schematic diagram of the signal receiving and demodulation terminal provided in an embodiment of the present invention. Figure 3 (a) is the schematic diagram of the signal receiving and demodulation terminal RX1, with the input being the detection resistor R. b1 The pickup voltages at both ends are filtered by a bandpass filter to remove system noise, and then pass through a detector diode and a parallel RC network to obtain the envelope of the modulated carrier signal. Finally, the obtained envelope is shaped by a hysteresis comparator to restore the digital signal. Figure 3 (b) is the schematic diagram of the signal receiving and demodulation terminal RX2, with the input being the detection resistor R. b2 The picked-up voltages at both ends are filtered by a bandpass filter to remove system noise. The demodulation circuit then performs A / D conversion on the input data, and finally the demodulation chip QCA6410 performs OFDM demodulation to restore the digital signal.

[0075] In this embodiment, the energy and signal coupling mechanisms use different coupling principles for transmission and are structurally separate. Therefore, the energy coupling mechanism and the signal coupling mechanism in this embodiment need to be modeled using different principle models. For the coupling mechanism of the MC-WPT system, the coupling mechanism should include a coil, a magnetic core, and a shielding metal plate. The shielding metal plate can be reused as one of the two pairs of coupling capacitor plates for the signal. Based on this, this embodiment will first model the energy coupling mechanism and then model the signal coupling mechanism based on the energy coupling mechanism.

[0076] In this embodiment, the coupling mechanism is applied to a freshwater environment. Since the conductivity of freshwater is greater than that of air, the MC-WPT system will experience eddy current losses in a freshwater environment. The losses generated in freshwater are also due to the electromagnetic induction produced by the freshwater in the primary coil, which receives energy through the magnetic field. Therefore, an equivalent model for the water eddy current losses can be obtained as follows: Figure 4 As shown, the loss model of underwater eddies is equivalent to an equivalent inductance L in the water. w A water equivalent resistance R is connected in series. w The voltage across the primary coil is u. p The self-inductance of the primary coil is L p The internal resistance of the primary coil is R. p The magnitude of the current flowing through the primary coil is I. p The equivalent current formed in the water circuit is I. w .

[0077] According to Kirchhoff's second law, the reflection impedance of the underwater loss circuit in the primary circuit can be obtained as:

[0078]

[0079] As can be seen from equation (1), the reflection impedance of the underwater loss circuit in the primary circuit is resistive and capacitive. This effect is mainly reflected in two aspects in the system: its capacitive part will affect the resonance condition of the system, and its resistive part will increase the loss of the system.

[0080] Under underwater flow loss conditions, in the equivalent model of the MC-WPT system, there exists equivalent eddy current resistance in both the primary and secondary loops, which affects the amplitude and phase of the mutual inductance, as follows:

[0081]

[0082] Where M represents the mutual inductance in the air, M wa For underwater mutual inductance, k is the coefficient of mutual inductance amplitude variation. Given the mutual inductance phase angle, the equivalent model of the MC-WPT system in the underwater environment can be obtained as follows: Figure 5 As shown, R wp R is the equivalent resistance of the water eddy current loss in the primary loop. ws L is the equivalent resistance of the water eddy current loss in the secondary circuit. s For the self-inductance of the secondary coil, R s The internal resistance of the secondary coil. Mutual inductance amplitude variation coefficient k, and the equivalent resistance of the primary and secondary eddy currents R. wp R ws Mutual inductance phase angle Since quantitative calculations are not possible, only qualitative analysis can be performed at this time, leading to two conclusions. Firstly, an increase in coil current will cause R... wp With R w The losses generated increase. Secondly, changes in mutual inductance affect the reflection impedance, thus affecting the resonance condition. The study in this literature found that the value of k is approximately equal to 1, while... The value of increases with the increase of transmission distance. Based on the above conclusions, to reduce the impact of water eddies on the MC-WPT system, the coil current should be minimized and the transmission distance reduced as much as possible.

[0083] Eddy currents in conductors dissipate as heat loss. The conductivity of the conductor that generates eddy currents affects the magnitude of eddy current loss; the higher the conductivity, the greater the eddy current generation. Table 1 shows the conductivity of different media at room temperature.

[0084] Table 1 Conductivity of different media at room temperature

[0085]

[0086] Therefore, under the same conditions, the eddy current loss in fresh water is less than that in seawater but greater than that in air, and its conductivity is very small and can be ignored. That is, in this embodiment, the following can be observed:

[0087]

[0088] Where M is the mutual inductance of the primary and secondary coils in the air.

[0089] According to the system's required output voltage U out With output power P out The secondary coil current I can be calculated based on the system characteristics. s for:

[0090]

[0091] This embodiment requires bidirectional high-speed signal transmission. A symmetrical coupling mechanism is more conducive to bidirectional signal transmission. Since one pair of signal coupling plates is multiplexed as a metal shielding plate for the energy coupling mechanism, the energy coupling mechanism must also be symmetrical. That is, the current I flowing through the primary and secondary sides... c :

[0092] I c =I p =I s (5)

[0093] The diameter c of the Leeds wire r The standard for Litz wire varies depending on the current flowing through it and its frequency. Different manufacturers provide different standards for Litz wire. The selection criteria should be based on the manufacturer's Litz wire selection manual and the secondary coil current I discussed in this article. c , power transmission frequency f e The wire diameter c can be determined. r If the coil is a circular coil, then the outer diameter of the primary and secondary coils is d. o In practical applications, due to the stress caused by bending of the wire, the coil cannot be fully wound to the center. Therefore, the inner diameter of the primary and secondary coils is taken as d based on the wire diameter. i To improve space utilization, the coil is tightly wound, so the number of turns N of the primary and secondary coils is:

[0094]

[0095] To reduce magnetic leakage, the magnetic core is placed tightly against the coil. A single, solid core is fragile and difficult to handle and manufacture; therefore, it is usually assembled from smaller cores. Thus, in engineering applications, magnetic cores are often square. To improve the self-inductance of the coil and the mutual inductance between coils, the side length d of the magnetic core is... r The outer diameter is equal to that of the coil. The metal shielding plate has the same shape as the magnetic core in engineering applications. All the above parameters are theoretical values ​​and can be adjusted appropriately according to actual conditions during manufacturing.

[0096] Based on the required transmission distance d and coil outer diameter d o Coil inner diameter d i Coil wire diameter c r The self-inductance L of the primary and secondary sides can be obtained by simulation software.p L s And the mutual inductance between coils M, i.e. M wa Therefore, the design flowchart of the energy coupling mechanism can be obtained as follows: Figure 6 As shown, the specific steps include:

[0097] E1. Determine the system output voltage U based on system requirements. out System output power P out , electrical energy transmission distance d, outer diameter d of the circular coil o ;

[0098] E2, according to U out P out Calculate the current in the primary coil, which is also the current in the secondary coil.

[0099] E3. According to the Litz wire selection manual provided by the manufacturer and the current I... c , power transmission frequency f e Determine the wire diameter c r ;

[0100] E4. According to wire diameter c r Determine the inner diameter d i According to the outer diameter d o Inner diameter d i wire diameter c r Determine the number of coil turns N;

[0101] E5. According to wire diameter c r Outer diameter d o Inner diameter d i The self-inductance L of the primary coil is obtained from the number of turns N and the energy transmission distance d. p The self-inductance L of the secondary coil s And the mutual inductance M between the primary and secondary coils wa .

[0102] The coupling mechanism of the MC-WPT system has been designed. For the EC-WPT system, the relative permittivity of fresh water is about 81 times that of air. Equation (7) is the capacitance formula of a parallel plate capacitor, where ε is the permittivity, S is the area of ​​the parallel plates facing each other, and d is the distance between the facing areas.

[0103]

[0104] According to equation (7), the coupling capacitance changes significantly when the medium changes from air to water. In air, the cross-coupling between two pairs of parallel plates is often negligible, but in an underwater environment, a strong edge effect occurs, requiring a capacitance calculation formula that considers the edge effect. This embodiment proposes a calculation formula derived using conformal mapping:

[0105]

[0106] Where ε is the dielectric constant, a is the width of the opposite plates, b is the length of the opposite plates, and d is the distance between the opposite areas. At this time, the cross-coupling capacitance will increase to a point that cannot be ignored. Therefore, the coupling mechanism design of the EC-WPT system needs to use a model that considers cross-coupling for the underwater environment. In the EC-WPT system, the transmission distance of the system is largely limited by the size of the coupling capacitance. Because air is not a good medium for capacitors, according to equation (8), to increase the coupling capacitance C, the side length of the plates must be increased. This will make the coupling mechanism of electric field coupling very bulky. However, when this system is applied underwater, this change in medium will significantly increase the coupling capacitance value of the system. For a planar dual-capacitor system, the large cross-coupling between the two pairs of plates will to some extent worsen the transmission effect of the system. Depending on the actual needs, additional structures or topologies may be needed to mitigate this effect. For a single-capacitor system whose transmission mechanism is not yet clear, the underwater environment greatly improves its transmission effect. Therefore, once the mechanism of the single-capacitor system is clear, it is likely to be more advantageous than the dual-capacitor EC-WPT system and the MC-WPT system.

[0107] Because the underwater environment greatly increases the capacitance between the various coupling components, which include a pair of metal shielding plates and a pair of external metal plates, capacitance will form between each pair of them. Therefore, the signal coupling mechanism model is as follows: Figure 7 As shown.

[0108] Although the location of the external metal plate is not yet determined, its presence in the system will inevitably cause [damage / contamination]. Figure 7 The coupled mechanism model, where C 12 C 34 These are the mutual capacitance capacitors between the two pairs of metal plates in the signal channel; they are responsible for signal transmission. 14 C 23 C is the cross-coupling capacitance between metal plates on different sides. 13 C 24 This refers to the self-capacitive capacitance between the metal plates on the same side. The impedance of a single metal plate is very small and can be ignored, so the capacitance formed by the metal plate and other parts can be considered as a direct connection in electrical terms. In this embodiment, the only desired capacitance is C. 12 With C 34In other studies of EC-WPT systems, both cross-coupling capacitance and self-capacitance hinder energy transfer and are undesirable. Therefore, the main design focus of this paper on the external metal plate is to reduce the capacitance. 12 With C 34 In addition, other capacitor values. Since the coupling mechanism is theoretically perfectly symmetrical, C... 14 With C 23 C 13 With C 24 The two sets of capacitors have the same value and change together.

[0109] After determining the signal coupling mechanism model, this embodiment proposes an external metal plate embedded within the inner diameter of the coil (hereinafter referred to as the embedded type) to achieve compatibility between the energy coupling mechanism and the signal coupling mechanism. A schematic diagram of the embedded coupling mechanism is shown below. Figure 8 As shown.

[0110] like Figure 8 As shown, the embedded type involves embedding an external metal plate into the inner diameter of the coil, structurally similar to the stacked structure in a dual-capacitor EC-WPT. This method utilizes the remaining space of the coupling mechanism, improving space utilization and achieving a hybrid channel coupling mechanism without increasing volume. If the external metal plate is large, the edge effect will be very obvious under the condition of a strong dielectric constant in water. Therefore, this structure has a smaller external metal plate, although it will reduce the area of ​​C. 34 Smaller, but still makes the capacitance C unfavorable for signal transmission. 14 C 23 C 13 C 24 The losses were also reduced, and the benefits outweighed the losses. Both the primary and secondary metal shielding plates used a side length of d. o The square electrode plate, with both the primary and secondary external metal plates having a side length of l a Square electrode plates.

[0111] The principle of wireless energy transmission is inductive magnetic coupling. A high-frequency alternating magnetic field emitted from the primary side induces an electromotive force on the secondary side, thereby generating an induced current in the circuit. A similar effect may occur when the energy coil interacts with the signal plate.

[0112] Figure 9 This represents the direction of the induced current generated on a metal plate when a high-frequency magnetic field passes through it under different conditions. Figure 9 (a) When there is no external circuit, the high-frequency magnetic field can only be dissipated in the metal as eddy currents when it passes through the metal plate. Figure 9(b) When a metal plate is connected to the circuit, a high-frequency magnetic field passing through the metal plate can generate a current flowing into the circuit in a fixed direction within the metal plate. In this embodiment, the signal circuit is externally connected to the metal plate that shields the magnetic field, so it is necessary to assess the extent to which energy interference affects the signal circuit in this way.

[0113] The magnetic induction effect between coils can be described using mutual inductance. Considering the metal plate as a coil, which is essentially a very wide and flat wire, COMSOL simulations based on this give a mutual inductance of 5.09 * 10⁻⁶. -4 uH. Figure 10 This is a cross-sectional view of the magnetic flux model for energy transfer in the coupling mechanism. The flux diagram shows that the main magnetic flux generated by the primary coil is distributed between the two coils, while there is almost no flux below the core of the primary coil; only a small amount of flux leaks to the metal plate from the edge of the core. This indicates that the core effectively confines the magnetic field lines, with only a small number of lines passing through the metal plate. Furthermore, the self-inductance of the metal plate is very small; even without the core's confinement of the field lines, the induced voltage on the metal plate would be very small. The mutual inductance between the metal plate and the coil also shows that the induced voltage on the metal plate will be in the millivolt range. Since the signal circuit consists entirely of capacitors, it is in a high-resistivity state for the energy signal, so the energy gain across the signal resistance is negligible.

[0114] Electric field coupling transmission utilizes the non-contact nature of capacitor plates to achieve wireless transmission. Conventional capacitors, to ensure small size and stable capacitance, use a dielectric with a relatively high permittivity and fix the relative positions of the two plates, resulting in a commonly seen single-piece capacitor. However, fundamentally, capacitors can also be constructed with non-fixed relative positions of the plates; air or water can also form a capacitor. These are the transmission plates in electric field coupling mechanisms.

[0115] Although the energy coil exhibits inductive properties, it is still made of wound metal conductors. Therefore, the coil can be indirectly considered as a metal plate, and capacitance exists between coils and between the coil and the metal plate. If the coil is considered as two metal plates, we can obtain... Figure 11 The 15-capacitor coupling model.

[0116] Depend on Figure 11 It is known that treating the coupling coil as a capacitor plate results in a particularly complex 15-capacitor coupling model. More importantly, energy cannot form a loop in the signal circuit, meaning that energy will not generate gain across the signal output resistance. However, in the theory of wireless power transfer, there exists a single-capacitor system, which uses only a pair of capacitor plates for energy transfer without needing to form a loop. Figure 11The capacitive coupling model satisfies the transmission conditions of a single-capacitor system. However, the transmission mechanism of a single-capacitor system is not yet clear, so the current single-capacitor model cannot accurately calculate the gain. Moreover, the energy transmission of a single-capacitor system has very high frequency requirements, generally above 500kHz. In this embodiment, the energy transmission frequency is 85kHz. The energy frequency itself is difficult to transmit in a single-capacitor system, and the signal loop is also in a high-impedance state with respect to energy, so the gain of energy on the signal monitoring resistor is also very small. However, high-frequency energy such as high-order harmonics and switching noise may exist in the energy loop, which can interfere with the signal through the high-pass signal loop. The amount and effect of these high-frequency noise interferences are also difficult to analyze and calculate, so this embodiment will ignore these interferences.

[0117] Figure 11 This can also be applied to coupled models of signal transmission. However, the coil itself is a large inductor, which is usually considered a high-impedance state for high-frequency signals in circuit analysis. Therefore, the signal will not pass through the capacitance formed by the coil and other parts. Thus, the simplified signal transmission model remains as follows: Figure 7 As shown.

[0118] Based on the above analysis and the determination of the system coupling mechanism model, this embodiment establishes circuit models for the energy loop and signal loop, thereby quantitatively obtaining the system's energy and signal gains. According to theoretical derivation, the influence trend of parameter changes on signal gain can be obtained, thus guiding the system's parameter design.

[0119] Based on the analysis above regarding energy interference with signals, although the forms of energy interference are diverse, the magnitude of the interference is negligible and cannot be quantified. Therefore, there is no need to consider the mutual interference model between energy and signals in the modeling. The energy loop and the signal loop can be established separately. The energy loop is modeled according to the MC-WPT system, and the signal loop is modeled according to the EC-WPT system, obtaining the transmission gain of energy and signal respectively.

[0120] Based on the freshwater model of the energy coupling mechanism, the equivalent circuit of the LCC-S compensated topology in a freshwater environment can be obtained. The energy transfer equivalent model is as follows: Figure 12 As shown, according to the LCC-S equivalent topology, we have:

[0121]

[0122] Among them, Z s R is the input impedance of the receiving end. e Let Z be the equivalent impedance at the input of the rectifier bridge, and ω be the system angular frequency. The system's reflection impedance Z... r :

[0123]

[0124] The total input impedance Z of the system in for:

[0125]

[0126] Let the system's input impedance Z in If the imaginary part is 0, then:

[0127]

[0128] Substituting equation (12) into equations (9)(10)(11), we get:

[0129]

[0130] According to the impedance calculation formula, the primary coil current can be obtained. With secondary coil current They are respectively:

[0131]

[0132]

[0133] in If the fundamental input voltage of the resonant network is given, then the equivalent load voltage can be obtained from equation (15). for:

[0134]

[0135] The voltage gain G of the underwater resonant network v It can be represented as:

[0136]

[0137] In reality, the coil's internal resistance R s Much smaller than the circuit's equivalent impedance R e Therefore, we can ignore R in equation (17). s Combining this with equation (3), the gain formula for the resonant network is obtained as follows:

[0138]

[0139] The input-output voltage relationship between the front and rear stages of a full-bridge inverter is as follows:

[0140]

[0141] The input-output relationship between the front and rear stages of a full-bridge rectifier is as follows:

[0142]

[0143] By combining equations (18), (19), and (20), we can obtain the DC input voltage U. dc With system output voltage U out The relationship between them is:

[0144]

[0145] From equation (21), it can be seen that, ignoring the coil internal resistance and with the mutual inductance M remaining constant, the system has a constant voltage output characteristic.

[0146] The underwater environment increases the capacitance between the plates, making the cross-coupling between the two pairs of plates non-negligible, thus requiring the establishment of a six-capacitor coupling model.

[0147] The six-capacitor coupling model is as follows Figure 13 As shown, take as Figure 4 The voltages at each point are U A U B U C U D , take U A The reference voltage, i.e., U A =0, U B =U1, U C -U D =U2. According to Kirchhoff's current law, we can obtain equation (22):

[0148]

[0149] Where ω s Given the signal transmission angular frequency, equation (22) can be simplified to equation (23):

[0150]

[0151] According to equation (23), the cross-coupled circuit model can be simplified as follows: Figure 14 The π-type equivalent circuit, where C x1 With C x2 For self-capacitance, C M For mutual capacitance, the formulas for each capacitance are shown in equation (24):

[0152]

[0153] Figure 14 Add a forward transmission signal source U to the cross-coupled equivalent circuit. s Signal output resistors R on both sides b1 With R b2 and R b2 Received voltage U Rb The signal detection voltage U can be obtained. Rb With signal input voltage Us Ratio:

[0154]

[0155] From equation (25), the forward signal transmission gain G can be obtained. s :

[0156]

[0157] Similarly, the reverse signal transmission gain G can be obtained. sf :

[0158]

[0159] In the coupling mechanism designed in this embodiment, the primary side and the secondary side are symmetrical structures, that is:

[0160]

[0161] Where C n For the self-compression between the two plates on the same side, C m This is the cross-coupling capacitor between two pairs of plates.

[0162] From equations (24) and (28), we can obtain the simplified formula for equation (29):

[0163]

[0164] When the signal output resistance is symmetrical and equal, that is:

[0165] R b1 =R b2 =R b (30)

[0166] Combining equations (26), (27), and (30), we can obtain that the forward transmission gain of the signal is equal to the reverse transmission gain, that is:

[0167]

[0168] Analysis of the signal gain expression (31) shows that when the signal output resistance R b With the signal transmission angular frequency ω s When the signal strength approaches 0, the signal transmission gain approaches 0; the signal output resistance R... b With the signal transmission angular frequency ω s As the signal approaches infinity, the signal transmission gain approaches the maximum gain G. smax :

[0169]

[0170] Figure 15The signal output resistance R is obtained through formula analysis. b Signal transmission gain G at different signal transmission frequencies s The relationship curve is shown in the figure. In the figure, f3 > f2 > f1. Based on theoretical analysis... Figure 15 It can be seen that the signal loop is a high-pass circuit, and the larger the value of the signal output resistance, the better it is for signal transmission.

[0171] Combining equation (28) and equation (31), we can obtain:

[0172]

[0173] From equation (33), it can be seen that when C n When the signal transmission gain G increases, s It will decrease; when C m When G increases, s It will first decrease and then increase. C n From a topological perspective, it is connected in parallel across the forward and reverse signal output resistors. Therefore, its presence will distribute the signal power across the signal output resistors. Increasing its value will reduce the power distributed across the signal output resistors, thus reducing the gain. C m The connection method tends to favor reverse suppression of the signal mutual capacitance, which will suppress C during the initial increase. 12 With C 34 The effect, in C m Increase to When C m As it continues to increase, it will become the main transmission capacitance of the signal, and C 12 With C 34 Instead, it becomes a cross-coupling capacitor that inhibits signal transmission, at which point, as C... m As the voltage increases, the signal gain will increase further, and the voltage across the load resistor will be in the opposite direction to the original voltage.

[0174] The system parameter design is described below. The overall parameter design process is as follows: Figure 16 As shown, the specific steps include:

[0175] S1. Determine the system output voltage U based on system requirements. out System output power P out Energy circuit operating frequency f e , electrical energy transmission distance d, outer diameter d of the circular coil o DC input voltage U dc ;

[0176] S2, determine L using steps E2 to E5. p L s And the mutual inductance M between the primary and secondary coils, i.e., M wa; Calculate the coupling capacitance C between the primary and secondary metal shielding plates based on the determined primary and secondary metal shielding plates. 12 ;

[0177] S3, according to M, U out U dc Calculate the series resonant inductance L r ; Calculate C based on the resonance relationship r C p C s According to the inner diameter d of the circular coil i Determine the side length l of the primary and secondary external metal plates. a ; Calculate the coupling capacitance C between the primary and secondary external metal plates based on the determined metal plates. 34 Self-containment C between primary metal plates 13 Self-containment C between secondary metal plates 24 The cross-coupling capacitance C between the primary and secondary metal plates 14 C 23 ;

[0178] S4. Determine if the output voltage reaches the target voltage; otherwise, decrease L. r Then re-evaluate; if yes, proceed to the next step; re-measure the mutual inductance M between the primary and secondary coils and determine whether the rate of change of mutual inductance ΔM is less than the set margin; if yes, proceed according to R... b Determining the effect curve on signal transmission R b If the value is not specified, proceed to the next step; otherwise, decrease l. a And recalculate C 34 C 13 C 24 C 14 C 23 Then reassess;

[0179] S5. Parameter design is complete; output L at this point. r l a .

[0180] System input voltage U dc System output voltage U out System output power P out Transmission distance is generally determined as a system performance parameter based on system requirements. Underwater equipment requires a watertight enclosure. Due to the size limitations of underwater equipment, the width of the watertight enclosure, i.e., the outer diameter d of the coil, is... o It was also determined that the inner diameter d of the coil i In engineering practice, a coil wire diameter of 20 times is selected. The operating frequency f of the energy circuit is obtained based on engineering experience. e The OFDM operating frequency band is selected based on the commonly used OFDM frequencies.

[0181] Based on the system design specifications and the coupling mechanism parameter design method, the self-inductance L of the primary coil can be obtained. p Secondary coil self-inductance L s Shielding metal plate inter-capacitance C 12 And mutual inductance M.

[0182] Now that the energy coupling mechanism parameters have been designed and the position of the external metal plate has been determined, we can explore the influence of its size on the coil parameters based on the engineering specifications and the coupling mechanism parameter design method. The engineering specifications include a DC input voltage of U. dc The system output voltage U is 50V (±5V). out The voltage is 100V (±10V), and the system output power P out The power supply is 200W (±20W), the transmission distance between the housings is 1cm, and the thickness of both the primary and secondary coil housings is 2cm. Therefore, the transmission distance d between the coils is 5cm, and the outer diameter d of the coil is... o It is 224cm.

[0183] like Figure 17 The image shown is based on COMSOL, with an additional metal plate having a side length of l. a With the self-inductance L of the primary coil p The relationship between the coil self-inductance and mutual inductance M. As can be seen from the figure, the coil self-inductance and mutual inductance decrease as the side length of the external metal plate increases, and the larger the side length of the external metal plate, the faster the coil parameters decrease. Therefore, the side length of the external metal plate should be as small as possible for the design of the energy coupling mechanism. According to the capacitance formula (8) considering the edge effect, when the side length of the metal plate approaches 0, the capacitance value will also approach 0. At this time, the mutual capacitance value is zero, and the channel will not be able to transmit signals. Therefore, when the side length of the metal plate is small, the side length of the metal plate should be increased as much as possible. In this embodiment, the side length of the external metal plate is very small relative to the shielding metal plate, so it should be increased as much as possible for signal transmission. The coil self-inductance and mutual inductance decrease more drastically when the side length of the external metal plate is greater than 4cm. At 4cm, the coil self-inductance decreases by 2.27% and the mutual inductance decreases by 4.90%. At 5cm, the coil self-inductance decreases by 4.41% and the mutual inductance decreases by 9.22%. In order to ensure the effectiveness of the energy coupling mechanism parameter design, the influence of the external metal plate on the mutual inductance should be limited. The system output voltage U out The permissible rate of change is 10%, according to equation (21), U out If the rate of change of M is consistent with that of M, then we take the rate of change of M, ΔM, as 5%, leaving a margin of 1, and then take the side length of the added metal plate at this time as l. a This ensures that the parameters of the energy coupling mechanism change within a small range, while also ensuring a certain degree of mutual capacitance between the external metal plates, thus guaranteeing the operation of the signal path.

[0184] From equation (21), we can obtain:

[0185]

[0186] The series resonant inductance L can be calculated from equation (34). r The value of .

[0187] C can be determined according to equation (12). r C p C s The value of .

[0188] Based on the coupling mechanism design and equation (8), the capacitance value C between the external metals can be determined. 34 Thus, the self-containment C between the metal plates on the same side is determined. 13 C 24 and cross-coupling capacitor C 14 C 23 Furthermore, the mutual inductance change rate ΔM is required to be less than 5%.

[0189] Based on the conclusion above, R b The value should be chosen to be as large as possible, but in order to reduce R b The risk of excessive size should be considered when selecting a size that meets the requirement of achieving G. smax R around 95% b The value is used as the signal output resistance value.

[0190] The system parameters shown in Table 2 can be obtained by following the above parameter design method and engineering parameter indicators, and these parameters will be used as simulation parameters.

[0191] Table 2 System Parameters

[0192]

[0193] Figure 18 This is a Simulink simulation diagram of the energy loop, which includes a DC power supply, inverter module, inverter drive module, resonant network, coupling mechanism, rectifier module, and load.

[0194] Figure 19 For the system to reach steady state, the inverter voltage u in With inverter current i in The waveforms are as follows: the voltage waveform is a square wave, and the current waveform is a sine wave, with almost no distortion, indicating that the system has achieved good resonance. Based on the phase relationship between the current and voltage, the subsequent circuit exhibits weak inductive behavior. In practical applications, weakly inductive circuits are more likely to ensure the reliability of system operation.

[0195] like Figure 20 The load voltage U is shown below. out with I outDuring the initial to steady-state response, the load voltage stabilizes slightly above the 100V mark, meaning the system's output power can reach the target power of 200W in steady state. During dynamic operation, voltage overshoot does not exceed 10%, and current overshoot does not exceed 5%. Wireless power supply systems typically operate for hours, so there are no high requirements for system settling time. However, due to the high power output, the system aims to minimize hardware stress due to overshoot. Therefore, in practical applications, soft-start or a gradual increase in input voltage is used to extend startup time and reduce system overshoot.

[0196] Figure 21 The Simulink simulation model of the signal loop includes the primary-side signal transmitting circuit TX1, the primary-side signal receiving circuit RX2, the primary-side switching circuit 1, the forward and reverse signal output resistors, the six-capacitor coupling model of the signal loop, the secondary-side signal receiving circuit RX1, the secondary-side signal transmitting circuit TX2, and the secondary-side switching circuit 2, where the switching circuit is used for the conversion between forward and reverse signal transmission.

[0197] Figure 22 For an embedded structure, the input signal generated by the signal generator during forward and reverse transmission is combined with the output signal obtained after signal transmission demodulation. Figure 22 (a) Corresponds to forward transmission. Figure 22 (b) Corresponding to reverse transmission. As can be seen from the segment captured in the figure, the signal was successfully transmitted and demodulated within this time range.

[0198] Simulation results show that both the parallel and embedded structures can achieve a maximum transmission speed of 60Mbps, verifying that the designed signal loop can be modulated and demodulated using OFDM modulation and can achieve high-speed signal transmission.

[0199] Figure 23 For a signal with an embedded structure, the waveforms are modulated and injected into the signal circuit during forward and reverse transmission, and the waveforms reach the signal output resistor after passing through the signal circuit. Figure 23 (a) Corresponds to forward transmission. Figure 23 (b) Corresponding to reverse transmission. By measuring the ratio of voltage amplitude at the corresponding positions, it can be obtained that the forward and reverse transmission gain of the signal loop is 0.26, which is consistent with the theoretical calculation.

[0200] The previous analysis showed that energy interference with signals can be divided into magnetic coupling and electric field coupling. Now, the parameters obtained from the parameter design will be substituted into the simulation model to verify the theoretical derivation.

[0201] Figure 24The interference voltage is generated across the signal output resistors on both sides of the signal circuit via magnetic coupling. As shown in the figure, the period of the interference waveform is the same as the period of the inverter voltage, proving that the interference is generated by energy. The amplitude of the interference voltage is approximately 0.1mV, indicating that the amplitude of the interference via magnetic coupling is very small, consistent with theoretical analysis, and can be almost ignored.

[0202] Figure 25 This refers to the interference voltage generated across the signal output resistor on both sides of the signal loop by energy in the form of electric field coupling. Since the energy cannot form a loop in the signal loop, the interference voltage of the energy on the signal is 0. This is consistent with the theoretical analysis.

[0203] In summary, the energy obtained from the simulation has almost no interference with the different coupling modes of the signal, so it is reasonable to ignore it in this embodiment and simplify the analysis.

[0204] In summary, this embodiment proposes an underwater parallel transmission system based on magnetic and electric fields for transmitting electrical energy and signals respectively. The system structure is presented, an energy and signal coupling mechanism model is established, a design method for the energy coupling mechanism is given, an embedded coupling mechanism structure is proposed, and the interference of energy on the signal is analyzed. An underwater energy loop topology is established based on MC-WPT system theory, and an underwater signal loop topology is established based on EC-WPT system theory. Expressions for the power transmission gain and signal transmission gain are given based on the AC impedance method and the system topology, and a method for designing system parameters is provided. A model is built and simulated on the MATLAB / Simulink simulation platform. Simulation results show that the system can achieve high-speed bidirectional signal transmission with almost no energy interference. The simulation results are basically consistent with the theoretical derivation, verifying the correctness and rationality of the proposed topology, model, and parameter design method, i.e., the system design method proposed in this embodiment.

[0205] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An underwater parallel transmission system based on magnetic and electric fields for transmitting electrical energy and signals respectively, characterized in that, The system includes a coupling mechanism comprising a symmetrically arranged primary structure and a secondary structure. The primary structure includes a primary metal shield, a primary coil, and a primary external metal plate disposed in a hollow region of the primary coil, arranged in layers. The secondary structure includes a secondary metal shield, a secondary coil, and a secondary external metal plate disposed in a hollow region of the secondary coil, arranged in layers. The primary and secondary coils are magnetically coupled to transmit electrical energy, and the primary metal shield, primary external metal plate, secondary metal shield, and secondary external metal plate are electrically coupled to transmit signals. Both the primary and secondary metal shields have a side length of d. o The square electrode plate, wherein both the primary external metal plate and the secondary external metal plate have a side length of l. a The primary coil and the secondary coil are both circular coils with an outer diameter of d. o The inner diameter is d i ; The system also includes a DC power supply, a high-frequency inverter, a primary compensation network, a secondary compensation network, a rectifier and filter circuit, and a load. The primary compensation network is connected to the primary coil, and the secondary compensation network is connected to the secondary coil. The primary compensation network adopts an LCC resonant network, specifically including a series resonant inductor L. r Primary series resonant capacitor C p and parallel resonant capacitor C r The secondary compensation network adopts an S-type compensation network, including a secondary series resonant capacitor C. s The system also includes a primary signal transmitting and receiving module and a primary signal detection resistor R connected to it. b1 and the connected secondary signal detection resistor R b2 Secondary signal transmitting and receiving module; the primary signal detection resistor R b1 The two ends are respectively connected to the primary metal shielding plate and the primary external metal plate, and the secondary signal detection resistor R b2 The two ends are respectively connected to the secondary metal shielding plate and the secondary external metal plate, and R has b1 =R b2 =R b ; The system parameters are designed using the following steps: S1. Determine the system output voltage U based on system requirements. out System output power P out Energy circuit operating frequency f e , electrical energy transmission distance d, outer diameter d of the circular coil o DC input voltage U dc ; S2. Determine the self-inductance L of the primary coil. p The self-inductance L of the secondary coil s And the mutual inductance M between the primary and secondary coils; calculate the coupling capacitance C between the primary and secondary metal shielding plates based on the determined primary and secondary metal shielding plates. 12 ; S3, according to M, U out U dc Calculate the series resonant inductance L r ; Calculate C based on the resonance relationship r C p C s According to the inner diameter d of the circular coil i Determine the side length l of the primary and secondary external metal plates. a ; Calculate the coupling capacitance C between the primary and secondary external metal plates based on the determined metal plates. 34 Self-containment C between primary metal plates 13 Self-containment C between secondary metal plates 24 The cross-coupling capacitance C between the primary and secondary metal plates 14 C 23 ; S4. Determine if the output voltage reaches the target voltage; otherwise, decrease L. r Then re-evaluate; if yes, proceed to the next step; re-measure the mutual inductance M between the primary and secondary coils and determine whether the rate of change of mutual inductance ∆M is less than the set margin; if yes, proceed according to R. b Determining the effect curve on signal transmission R b If the value is not specified, proceed to the next step; otherwise, decrease l. a And recalculate C 34 C 13 C 24 C 14 C 23 Then reassess; S5. Parameter design is complete; output L at this point. r l a .

2. The underwater parallel transmission system based on magnetic field and electric field for transmitting electrical energy and signals respectively, as described in claim 1, is characterized in that: The diameter of the circular coil is c. r The number of turns is N; the parameter design steps for the primary coil and the secondary coil are as follows: E1. Determine the system output voltage U based on system requirements. out System output power P out , electrical energy transmission distance d, outer diameter d of the circular coil o ; E2, according to U out P out Calculate the current in the primary coil, which is also the current in the secondary coil. ; E3. According to the Litz wire selection manual provided by the manufacturer and the current I... c , power transmission frequency f e Determine the wire diameter c r ; E4. According to wire diameter c r Determine the inner diameter d i According to the outer diameter d o Inner diameter d i wire diameter c r Determine the number of coil turns ; E5. According to wire diameter c r Outer diameter d o Inner diameter d i The self-inductance L of the primary coil is obtained from the number of turns N and the power transmission distance d. p The self-inductance L of the secondary coil s And the mutual inductance M between the primary coil and the secondary coil.

3. The underwater parallel transmission system based on magnetic field and electric field for transmitting electrical energy and signals respectively, as described in claim 1, is characterized in that: In step S3, according to the formula Calculate L r ; C is calculated according to the following formula. 12 C 34 C 13 C 24 C 14 C 23 Any capacitance value C in: ， Where ε is the dielectric constant of the freshwater environment, a is the width of the directly opposite portion of the plates, b is the length of the directly opposite portion of the plates, and d is the distance between the directly opposite portions of the plates.

4. The underwater parallel transmission system based on magnetic and electric fields for transmitting electrical energy and signals respectively, as described in claim 1, is characterized in that... In step S4, according to R b Determining the effect curve on signal transmission R b The value is specifically: select one that can achieve 95% G. smax R b Value, G smax This indicates the maximum gain of the signal transmission.

5. The underwater parallel transmission system based on magnetic field and electric field for transmitting electrical energy and signal respectively, as described in claim 4, is characterized in that: C 13 C 24 C 14 C 23 satisfy: ， G smax Calculated by the following formula: ， in, All are equivalent capacitances.

6. The underwater parallel transmission system based on magnetic field and electric field for transmitting electrical energy and signals respectively, as described in claim 1, is characterized in that: The primary signal transmitting and receiving module includes a primary signal transmitting circuit, a primary signal receiving circuit, and a primary switching circuit; the secondary signal transmitting and receiving module includes a secondary signal transmitting circuit, a secondary signal receiving circuit, and a secondary switching circuit. The primary switching circuit controls the primary signal transmitting circuit to connect the primary signal detection resistor R. b1 During signal transmission, the secondary switching circuit controls the secondary signal receiving circuit to connect the secondary signal detection resistor R. b2 It performs signal reception, enabling forward signal transmission from primary to secondary. The secondary switching circuit controls the secondary signal transmitting circuit to connect the secondary signal detection resistor R. b2 To transmit a signal, the primary switching circuit controls the primary signal receiving circuit to connect the primary signal detection resistor R. b1 It receives signals and enables reverse transmission of signals from the secondary to the primary stage.

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