Electric energy and information parallel transmission system and underwater application parameter design method thereof

Abstract

The invention provides an electric energy and information parallel transmission system and an underwater application parameter design method thereof.The system comprises a primary side power coil, a primary side relay coil, a secondary side relay coil and a secondary side power coil, and a primary side relay compensation circuit and a primary side relay series LC circuit are connected to the primary side relay coil; a secondary relay compensation circuit and a secondary relay series LC circuit are connected to the secondary relay coil, the primary power coil and the primary relay coil are coaxially and coplanar arranged, and the secondary power coil and the secondary relay coil are coaxially and coplanar arranged. A primary side information transmitting circuit and a primary side information receiving circuit are further connected to the primary side relay series LC circuit in a half-duplex communication mode through a first switching circuit, and a secondary side information transmitting circuit and a secondary side information receiving circuit are further connected to the secondary side relay series LC circuit in a half-duplex communication mode through a second switching circuit. The method has the advantages that the voltage stress of the information transmission circuit can be reduced, and crosstalk between electric energy and an information transmission channel can be reduced.

Description

Technical Field

[0001] The invention relates to the field of wireless power transmission, and in particular to an electric energy and information parallel transmission system and an underwater application parameter design method thereof. Background Art

[0002] With the growing demand for ocean monitoring and ocean energy detection, people have put forward higher requirements for flexible and safe power supply for underwater electrical equipment (such as underwater sensors, underwater autonomous submersibles, underwater remote control equipment, etc.). Existing power supply often adopts wet plugging and unplugging of cables and manual salvage on shore, which have shortcomings such as short life, high price and inconvenient maintenance. Wireless power transfer (WPT) technology has become a new solution due to its convenience and flexibility. The current research is mainly divided into magnetic-field coupled wireless power transfer (MC-WPT) technology and electric-field coupled wireless power transfer (EC-WPT) technology. Due to its early start, relevant experts and scholars have achieved many research results in all-round wireless power transmission, analysis and suppression of the impact of metal on MC-WPT system, and application in special underwater environments. At the same time, since underwater electrical equipment needs to exchange information with the base station to achieve command issuance, data feedback, closed-loop control, etc., magnetic-field coupled underwater wireless power and information parallel transmission (Magnetic-field Coupled Underwater Simultaneous Wireless Power and Information Transfer, MC-USWPIT) technology has become a new hot research direction.

[0003] However, the existing MC-USWPIT system is still far from meeting many engineering requirements in terms of transmission distance, transmission power and information transmission speed. Existing technologies are generally unable to meet the requirements of long-distance, high-power and high-speed two-way information transmission between base stations and electrical equipment in underwater environments. Summary of the invention

[0004] In view of this, the present invention first provides a parallel transmission system of electric energy and information, which mainly focuses on the rapid wireless power supply and high-speed two-way information transmission needs of electrical equipment such as unmanned submersibles in seawater environments, so that it can simultaneously achieve high-power electric energy transmission and high-speed two-way information transmission over a large transmission distance.

[0005] In order to achieve the above object, the specific technical solutions adopted by the present invention are as follows:

[0006] A power and information parallel transmission system comprises a primary power coil, a primary relay coil, a secondary power coil and a secondary relay coil, wherein a wireless power transmitting circuit is connected to the primary power coil, a primary relay compensation circuit and a primary relay series LC circuit are connected to the primary relay coil, a wireless power receiving circuit is connected to the secondary power coil, and a secondary relay compensation circuit and a secondary relay series LC circuit are connected to the secondary relay coil. The key lies in that: the primary power coil and the primary relay coil are coaxially and coplanarly arranged, the secondary power coil and the secondary relay coil are coaxially and coplanarly arranged, the primary information transmitting circuit and the primary information receiving circuit are connected to the primary relay series LC circuit through a first switching circuit half-duplex communication mode, and the secondary information transmitting circuit and the secondary information receiving circuit are connected to the secondary relay series LC circuit through a second switching circuit half-duplex communication mode.

[0007] Optionally, the wireless power transmitting circuit includes a DC power supply, a high-frequency inverter and a primary-side compensation circuit, and the wireless power receiving circuit includes a secondary-side compensation circuit, a rectifier and filter circuit and a power load.

[0008] Optionally, the primary side compensation circuit, the primary side relay compensation circuit, the secondary side compensation circuit and the secondary side relay compensation circuit all adopt SS type compensation.

[0009] Optionally, the primary-side relay compensation circuit adds a primary-side relay series LC circuit, and the secondary-side relay compensation circuit adds a secondary-side relay series LC circuit.

[0010] Optionally, a primary-side wave-blocking capacitor is provided between the first switching circuit and the primary-side relay compensation circuit, and a secondary-side wave-blocking capacitor is provided between the second switching circuit and the secondary-side relay compensation circuit.

[0011] Optionally, the system resonance condition satisfies:

[0012] as well as in:

[0013] ω p is the angular frequency of the power transmission channel, L1 is the self-inductance of the primary power coil, L2 is the self-inductance of the primary relay coil, L3 is the self-inductance of the secondary relay coil, L4 is the self-inductance of the secondary power coil, C1 is the primary compensation capacitor value connected in series with the primary power coil, C2 is the primary relay compensation capacitor value, C3 is the secondary relay compensation capacitor value, C4 is the secondary compensation capacitor value connected in series with the secondary power coil, L s1 is the inductance value of the primary relay series LC circuit, Cs1 is the capacitance value of the primary relay series LC circuit, L s2 is the inductance value of the secondary-side relay series LC circuit, C s2 is the capacitance value of the secondary side relay series LC circuit.

[0014] Optionally, the primary power coil, the primary relay coil, the secondary power coil and the secondary relay coil are designed with a symmetrical coupling structure and satisfy L1=L4, L2=L3, M 12 =M 34 and M 13 =M 24 ,in:

[0015] L1 is the self-inductance of the primary power coil, L2 is the self-inductance of the primary relay coil, L3 is the self-inductance of the secondary relay coil, L4 is the self-inductance of the secondary power coil, M 12 is the mutual inductance between the primary power coil and the primary relay coil, M 34 is the mutual inductance between the secondary power coil and the secondary relay coil, M 13 is the mutual inductance between the primary power coil and the secondary relay coil, M 24 is the mutual inductance between the primary relay coil and the secondary power coil. All the above parameters are obtained in an underwater environment.

[0016] Optionally, the primary side wave blocking capacitor and the secondary side wave blocking capacitor satisfy:

[0017] Where: s is the angular frequency of the information transmission channel, C ss1 is the primary side wave blocking capacitor value, C ss2 is the secondary side wave blocking capacitor value.

[0018] Based on the above system, another object of the present invention is to provide a method for designing underwater application parameters of a power and information parallel transmission system, the key of which is that it includes the following steps:

[0019] S1: Set the system output power, transmission distance and resonant frequency of the power transmission channel according to the system's underwater application scenario working indicators;

[0020] S2: Set the system power frequency to satisfy the condition that the power transmission channel voltage gain = 1;

[0021] S3: Determine the size of the coupling mechanism and the number of coil turns according to the installation space of the system's underwater application scenario;

[0022] S4: Determine the self-inductance of each coil and the mutual inductance between them through finite element simulation and circuit simulation;

[0023] S5: determining the capacitance value of each compensation capacitor according to the resonance condition;

[0024] S6: setting the resonant frequency of the information transmission channel according to the underwater application scenario of the system, so as to satisfy the condition that the ratio of the system power frequency to the resonant frequency of the information transmission channel approaches 0;

[0025] S7: determining the inductance value in the primary-side relay series LC circuit and the inductance value in the secondary-side relay series LC circuit according to the voltage gain of the information transmission channel;

[0026] S8: Determine the capacitance value in the primary-side relay series LC circuit, the capacitance value in the secondary-side relay series LC circuit, the primary-side wave-blocking capacitance value, and the secondary-side wave-blocking capacitance value according to the resonance condition;

[0027] S9: Output all system parameters.

[0028] Optionally, when determining the voltage gain of the power transmission channel and the voltage gain of the information transmission channel, the eddy current loss equivalent resistance of each coil in the underwater environment is taken into account in the corresponding equivalent circuit.

[0029] The remarkable effects of the present invention are:

[0030] The present invention realizes information transmission on the relay coil of the power transmission channel, which not only reduces the voltage stress of the information transmission circuit, but also helps to reduce the crosstalk between the power transmission channel and the information transmission channel. In particular, when the information transmission channel adopts a series LC circuit to inject information, according to the parameter design method, the LC circuit is completely resonated at the power transmission frequency, thereby reducing the influence of the power transmission channel on the information transmission channel. Only a very small capacitance blocking capacitor can be used to further reduce the crosstalk between the power transmission channel and the information transmission channel and the voltage stress of the information transmission channel, thereby reducing the design difficulty of the system. In addition, parameter design according to the method proposed in the present invention not only reduces the eddy current loss caused by the underwater environment, but also helps to achieve the system The improvement of transmission distance, transmission power and information transmission rate is improved at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings of the present invention are as follows.

[0032] Figure 1 is a schematic diagram of a coplanar relay coil type coupling structure in a specific embodiment of the present invention;

[0033] Figure 2 is a system circuit topology diagram in a specific embodiment of the present invention;

[0034] Figure 3 It is a system equivalent circuit model diagram in a specific embodiment of the present invention.

[0035] Figure 4 is an equivalent circuit model diagram of an electric energy transmission channel in a specific embodiment of the present invention;

[0036] Figure 5 is an equivalent circuit model diagram of an information forward transmission channel in a specific embodiment of the present invention;

[0037] Figure 6 yes Figure 5 The equivalent circuit of

[0038] Figure 7 It is a parameter design flow chart in a specific embodiment of the present invention;

[0039] Figure 8 is the voltage u during the experimental test in 、u o and current i1, i4 waveforms (no information transmission channel);

[0040] Fig. 9 This is the display interface diagram of the power analyzer during experimental testing (without information transmission channel);

[0041] Fig.10 is the voltage u during the experimental test in 、u o and current i1, i4 waveforms (with information transmission);

[0042] Fig.11 It is the display interface of the power analyzer during experimental testing (with information transmission). DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0044] This embodiment first provides a power and information parallel transmission system, including a primary power coil, a primary relay coil, a secondary power coil and a secondary relay coil. In specific implementation, the primary power coil, the primary relay coil, the secondary power coil and the secondary relay coil constitute Figure 1The four-coil coplanar coupling mechanism shown in the figure, wherein the transmitting end coupling mechanism and the receiving end coupling mechanism are composed of two square coils (L1, L2 and L3, L4) placed in the same plane, the primary side (transmitting end) power coil and the primary side (transmitting end) relay coil are coaxially coplanarly arranged, and the secondary side (receiving end) power coil and the secondary side (receiving end) relay coil are coaxially coplanarly arranged. In the MC-USWPIT system, L1 is connected to the transmitting end compensation circuit, inverter and DC power supply, L4 is connected to the receiving end compensation circuit, rectifier filter circuit and electrical equipment, L2 is connected to the transmitting end relay compensation circuit and the transmitting end information injection / extraction circuit, L3 is connected to the receiving end relay compensation circuit and the receiving end information extraction / injection circuit, and there is cross coupling between the four coils. With respect to power transmission, the equivalent circuit, working characteristics and analysis method of the MC-WPT system using this coupling mechanism are similar to those of the traditional multi-relay MC-WPT system. Therefore, the coupling mechanism used in this embodiment is called a coplanar relay coil type coupling mechanism, L1 and L4 are the power coils at the transmitting end and the receiving end respectively, and L2 and L3 are the relay coils at the transmitting end and the receiving end respectively. The coils are made of a wire with a diameter of l m The Litz wire is wound evenly. l1 and l2 represent the side lengths of the two coils at the transmitting end, l3 and l4 represent the side lengths of the two coils at the receiving end, and d represents the transmission distance of the system. In order to reduce magnetic leakage and improve the coupling performance between the coils, a magnetic core is laid on the back of the coupling mechanism at the transmitting end and the receiving end.

[0045] Combination Figure 2 It can be seen that the above coupling structure is used to build a wireless power and information parallel transmission system. Since the SS type compensation circuit has the advantages of simple structure, high power density and low cost, this embodiment adopts SS type compensation. The system mainly consists of a DC power supply U dc , voltage type full bridge inverter (S1~S4), transmitting end power coil L1, transmitting end relay coil L2, receiving end relay coil L3, receiving end power coil L4, transmitting end compensation capacitor C1, transmitting end relay compensation capacitor C2, receiving end relay compensation capacitor C3, receiving end compensation capacitor C4, uncontrolled rectifier bridge (D1~D4), filter capacitor C L , load equivalent resistance R L , transmitter relay series LC circuit (L s1 , C s1 ), receiving end relay series LC circuit (L s2 , C s2 ), transmitter information transmission circuit TX1, transmitter information receiving circuit RX1, transmitter wave blocking capacitor C ss1 、Receiving end wave blocking capacitor C ss2, a receiving end information receiving circuit RX2, a receiving end information transmitting circuit TX2, a transmitting end switching circuit and a receiving end switching circuit.

[0046] The present invention adopts a half-duplex communication mode, mainly because it has the advantages of good fault tolerance, low cost, and is more conducive to reducing the crosstalk between electric energy and information. When information is transmitted in the forward direction, the a1 end in the switching circuit is connected to the b1 end, and the a2 end is connected to the c2 end; when information is transmitted in the reverse direction, the a1 end in the switching circuit is connected to the c1 end, and the a2 end is connected to the b2 end. The switching of the information transmission direction can be realized by a multi-way switch chip such as a gate chip CD4051, 74HC153, etc.

[0047] In order to further understand the working principle of the above system, the following system analysis and modeling are carried out:

[0048] The MC-USWPIT system relies on the alternating magnetic field generated by the high-frequency alternating current in the coil to transmit power and realize information exchange between the transmitter and the receiver. The main influence of the water medium on the magnetic field transmission is the conductivity. The comparison of air, fresh water and seawater parameters is shown in Table 1. As can be seen from the table, there is a significant difference in the conductivity of seawater medium and air. For the MC-USWPIT system, the time-varying magnetic field will cause large eddy current losses in highly conductive seawater. The current literature analysis often equates eddy current losses to losses on eddy current loss resistors.

[0049] Table 1 Comparison of air, fresh water and sea water parameters

[0050]

[0051] For the power transmission channel, the voltage-type full-bridge inverter can convert the DC voltage into a square wave voltage, and use the fundamental wave analysis method to convert it into a voltage source u in , rectifier filter circuit and load equivalent resistance R L Equivalent to R eq , the information transmission circuit is equivalent to a voltage source u s1 and u s2 , the information receiving circuit is equivalent to the resistor R s1 and R s2 .u in With R eq As shown in formula (1):

[0052]

[0053] According to the above analysis, Figure 2 The topology can get the equivalent circuit of the system as Figure 3 shown.

[0054] Figure 3 In, M 12 ~M34 is the mutual inductance between the coupling mechanism coils in the underwater environment, r1~r4 are the equivalent internal resistances considering the eddy current loss of seawater, and r s1 、r s2 is the equivalent internal resistance of the series LC circuit. The information transmission channel in this system is a symmetrical structure, and the forward and reverse transmission characteristics of information are similar. Therefore, this embodiment only takes the forward transmission of information as an example for analysis. According to the superposition theorem, when transmitting electric energy, the information source is regarded as a short circuit, and the Kirchhoff voltage equation is written as formula (2):

[0055]

[0056] Among them, ω p is the angular frequency of the power transmission channel, and the loop impedances Z1, Z2, Z3 and Z4 on the transmitting end power coil, the transmitting end relay coil, the receiving end relay coil and the receiving end power coil are given by formula (3):

[0057]

[0058] Among them, “||” represents parallel connection, and the system resonance condition satisfies equation (4):

[0059]

[0060] Depend on Figure 3 It can be seen that the loss of the system power transmission channel P loss Mainly introduced by the internal resistance of the inductor, P loss Formula (5):

[0061]

[0062] From formula (5), we can see that in order to reduce the loss introduced by the series LC circuit, L s1 and L s2 The internal resistance should be as small as possible, and the resonance condition of the series LC circuit should satisfy equation (6):

[0063]

[0064] When satisfying equation (6) and the inductor internal resistance (r s1 、r s2 ) is small enough, the transmitter and receiver relay circuits are connected in series with an LC circuit (L s1 , C s1 and L s2 , C s2 ) is approximately short-circuited when analyzing the power transmission channel, and the equivalent circuit of the power transmission channel is obtained as follows Figure 4 shown.

[0065] In order to simplify the system design, a symmetrical coupling mechanism can be used, that is, L1 = L4, L2 = L3, M 12 =M 34 and M 13 =M 24 In this case, the system output power P o With the voltage gain G p As shown in formula (7):

[0066]

[0067] Among them, the intermediate variables X and Y are shown in formula (8):

[0068]

[0069] The coupling coefficient k ij =M ij / (L i L j ) 1 / 2 .

[0070] For the information transmission channel, taking the forward transmission of information as an example, according to the superposition theorem, when analyzing the information transmission channel, the voltage-type full-bridge inverter can be regarded as a short circuit. The equivalent circuit of the forward transmission of information is as follows: Figure 5 shown.

[0071] Define γ as the angular frequency ω of the power transmission channel p and the information transmission channel angular frequency ω s The ratio is as shown in formula (9):

[0072]

[0073] From formula (9), we can get that the relay coil is connected in series with the LC circuit (L s1 , C s1 and L s2 , C s2 ) The impedance Z5 and Z6 for information transmission are given by formula (10):

[0074]

[0075] From formula (10), we can see that when γ approaches 0, the impedance of the relay coil series LC circuit at the information transmission frequency is approximately equal to the inductance L s1 and L s2 .

[0076] For the MC-USWPIT system, the system resonant frequency f pIt is generally set below 20kHz, which can effectively reduce the impact of seawater on the power transmission of the MC-USWPIT system. In order to reduce the crosstalk between the information transmission channel and the power transmission channel and improve the information transmission rate and transmission stability, the operating frequency of the information transmission channel is generally set above MHz. Therefore, γ satisfies the condition of approaching 0.

[0077] Under the condition that γ approaches 0, the resonance condition of the information transmission channel satisfies equation (11):

[0078]

[0079] Capacitor C ss1 and C ss2 The impedance at the power transmission channel frequency is expressed as (12):

[0080]

[0081] From formula (12), we can see that when γ approaches 0, the capacitance C ss1 and C ss2 The impedance of the power transmission channel at the operating frequency is very large, which helps to reduce the crosstalk between the power transmission channel and the information transmission channel and simplifies the design of the information transmission channel under higher power power transmission conditions.

[0082] Capacitors C1 to C4 are usually in nF level, which can be regarded as short circuit for information carrier with frequency of MHz level. Based on the above analysis, the equivalent circuit of simplified information transmission channel can be obtained as follows: Figure 6 As shown in the figure. eq1 =r1+r2, r eq2 =r3+r4.

[0083] According to the existing analysis method, the equivalent self-inductance L of the transmitter can be obtained. eq1 , receiving end equivalent self-inductance L eq2 , equivalent mutual inductance M eq The expression of is formula (13):

[0084]

[0085] To simplify the analysis, ignoring the internal resistance of the coil, the voltage gain G of the information transmission channel can be obtained: s Formula (14):

[0086]

[0087] Based on the above system, this embodiment also provides a parameter design method for its underwater application. Specifically, according to the system output power P o , the transmission distance d required and the coupling mechanism installation size limitation, the system resonant frequency f is givenp , system operating frequency f, information transmission frequency f s , the number of turns of the coupling mechanism coil N1~N4, the side length of the coupling mechanism l1~l4, the self-inductance of the coil L1~L4, the compensation capacitor C1~C4, the mutual inductance of the coil M 12 ~M 34 , L of the series LC circuit s1 , C s1 and L s2 , C s2 、Surge-blocking capacitor C ss1 , C ss2 Based on the analysis in the previous article, the parameter design flow chart of the system is given as follows: Figure 7 As shown, the specific steps include:

[0088] S1: Set the system output power, transmission distance and resonant frequency of the power transmission channel according to the system's underwater application scenario working indicators;

[0089] S2: Set the system power frequency to satisfy the condition that the power transmission channel voltage gain = 1;

[0090] S3: Determine the size of the coupling mechanism and the number of coil turns according to the installation space of the system's underwater application scenario;

[0091] S4: Determine the self-inductance of each coil and the mutual inductance between them through finite element simulation and circuit simulation;

[0092] S5: determining the capacitance value of each compensation capacitor according to the resonance condition;

[0093] S6: setting the resonant frequency of the information transmission channel according to the underwater application scenario of the system, so as to satisfy the condition that the ratio of the system power frequency to the resonant frequency of the information transmission channel approaches 0;

[0094] S7: determining the inductance value in the primary-side relay series LC circuit and the inductance value in the secondary-side relay series LC circuit according to the voltage gain of the information transmission channel;

[0095] S8: Determine the capacitance value in the primary-side relay series LC circuit, the capacitance value in the secondary-side relay series LC circuit, the primary-side wave-blocking capacitance value, and the secondary-side wave-blocking capacitance value according to the resonance condition;

[0096] S9: Output all system parameters.

[0097] Specifically, when determining the voltage gain of the power transmission channel and the voltage gain of the information transmission channel, the eddy current loss equivalent internal resistance of each coil in the underwater environment is considered in the corresponding equivalent circuit.

[0098] In order to further understand the technical effects of the present invention, Figure 2 The system topology and Figure 7 A set of experimental device with an output power of 5 kW was built by using the parameter design method. The system parameters of the experimental device are shown in Table 2. In the table, L1~L4 and mutual inductance M 12 -M 34 The coupling mechanism was placed in water using a watertight lead-out line and measured by an LCR-8230 bridge tester, while other component parameters were measured in an air environment.

[0099] Table 2 System parameters

[0100]

[0101] The DC power supply model used in the experimental device is IT-M3912D-800-48, the electronic load model is N35218-1500-40, the switch tube MOSFET model used in the voltage-type full-bridge inverter is C3M0021120K, the rectifier is composed of 4 SiC diodes GHXS030A120S, and a 100mm*100mm*5mm ferrite core is fully spread on the back of the coil. The information transmission / reception circuit of the transmitter and the receiver selects two LW-MPA223 power communication modules. The module is connected to the PC through a network cable. The L line and N line on the module are twisted and connected to the relay coil through a filtering network. The module and the PC constitute the information transmission / reception part. The information modulation method adopts Orthogonal frequency-division multiplexing (OFDM), which is a multi-carrier modulation technology that converts a single-carrier serial information stream into a multi-carrier parallel information stream, which is conducive to improving the information transmission speed. In the experiment, the change of information transmission direction is switched manually.

[0102] The laboratory uses a coupling mechanism that simulates the seawater test environment. The power coils and relay coils at the transmitting and receiving ends are watertightly treated with Ausbond150 two-component epoxy resin potting glue. Seawater is simulated by adding sea salt to fresh water, and the conductivity is measured by a SUP-8.0 conductivity meter.

[0103] Through testing, in a simulated seawater experimental environment with a conductivity of 4.15S / m and a transmission distance of 50cm, the output voltage and current of the voltage-type full-bridge inverter with only the power transmission channel and the input voltage and current waveforms before the rectifier are as follows Figure 8 As shown in the figure, the system works in a good resonant state. The current waveform lags slightly behind the voltage waveform, and the system is weakly inductive, which makes it easier for the system to achieve ZVS.

[0104] The system transmission power and efficiency are measured by the PW8001 power analyzer. The power analyzer display interface is as follows: Fig. 9The system input power is 6.08kW, the system output power is 5.18kW, and the power transmission efficiency is 85.15%.

[0105] When there is an information transmission channel and information is transmitted in the forward direction, the output voltage and current of the voltage-type full-bridge inverter and the input voltage and current waveforms before the rectifier are as follows: Fig.10 As shown in the experimental waveform, it can be seen that adding information transmission has little effect on power transmission.

[0106] The display interface of the power analyzer with information transmission is as follows Fig.11 As shown, after adding the information transmission channel, the system input power is 6.38kW, the system output power is 5.33kW, and the power transmission efficiency is 83.58%.

[0107] Since the signal carrier frequency of the experimental system is very high and it uses OFDM modulation, it is difficult to directly observe the information transmission rate and bit error rate from the experimental test waveform, so the system information parallel transmission performance test is carried out through two PCs in the experiment. In order to intuitively demonstrate the information transmission speed, a local area network is built between the two PCs using the information transmission channel, and a shared folder is built based on this local area network to upload and download files. The performance of the system information transmission channel is verified by observing the transmission speed of writing files to the receiving folder and checking whether the source file is consistent with the received file.

[0108] When the electric energy output power is 5.33kW, the information receiving end PC displays the measured information transmission rate as 710Kbyte / s (5.68Mbit / s).

[0109] Furthermore, the system performance was tested under the conditions of 30, 40 and 50 cm transmission distances while simulating a seawater conductivity of 4S / m and ensuring that the system output power was basically maintained at 5kW; the system performance was also tested under the conditions of 50 cm transmission distance and ensuring that the system output power was basically maintained at 5kW and simulating seawater conductivity of 4, 5 and 6S / m. The test results are shown in Table 3. It is worth mentioning that when doing experiments with changes in transmission distance, since the coupling of the system will change significantly with changes in transmission distance, the system parameters need to be reset according to the design method proposed in this paper.

[0110] It can be seen from Table 3 that, under the same output power and constant conductivity, the system's power transmission efficiency and information transmission rate increase with the decrease in distance, especially the information transmission rate, which reaches 1090Kbyte / s (8.72Mbit / s) at 30cm. Under the same output power and constant transmission distance, as the simulated seawater conductivity increases, the eddy current loss of the system increases, and the system's power transmission efficiency and information transmission rate decrease with the increase in conductivity, but the power transmission efficiency still reaches 81.38%, and the information transmission rate reaches 298Kbyte / s (2.38Mbit / s). The system still has good power transmission performance and high information transmission rate. The above experiments also further prove that in the seawater environment, it is very difficult to simultaneously improve the system's transmission power, transmission distance and information transmission rate.

[0111] Table 3 System performance under different conditions

[0112]

[0113] During the experiment, the transmission direction of information was changed by manual switching, and the experimental content of the above-mentioned information forward transmission was also tested. The test results under reverse information transmission were similar to those under forward information transmission.

[0114] In summary, it can be seen that the present invention proposes a power and information parallel transmission system and its underwater application parameter design method, which reduces the voltage stress of the information transmission circuit and helps to reduce the crosstalk between the power transmission channel and the information transmission channel by realizing the transmission of information on the relay coil; by adopting the method of injecting information in series LC circuit in the information transmission channel, the LC circuit is fully compensated at the power transmission frequency, and only adopting the wave-blocking capacitor with smaller capacitance further reduces the crosstalk between the power transmission channel and the information transmission channel and the voltage stress of the information transmission channel, thereby reducing the design difficulty of the system; based on the system modeling analysis, an equivalent circuit model of the power transmission channel and the information transmission channel and a parameter design method of the system are given, by which the eddy current loss caused by the seawater environment is reduced and it helps to reduce the influence of high-power power transmission on the information transmission speed.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A power and information parallel transmission system, comprising a primary power coil, a primary relay coil, a secondary relay coil and a secondary power coil, wherein a wireless power transmitting circuit is connected to the primary power coil, a primary relay compensation circuit and a primary relay series LC circuit are connected to the primary relay coil, a wireless power receiving circuit is connected to the secondary power coil, and a secondary relay compensation circuit and a secondary relay series LC circuit are connected to the secondary relay coil, characterized in that: The primary power coil and the primary relay coil are coaxially and coplanarly arranged, the secondary power coil and the secondary relay coil are coaxially and coplanarly arranged, and the primary information transmitting circuit and the primary information receiving circuit are also connected to the primary relay series LC circuit through a first switching circuit half-duplex communication mode, and the secondary information transmitting circuit and the secondary information receiving circuit are also connected to the secondary relay series LC circuit through a second switching circuit half-duplex communication mode.

2. The power and information parallel transmission system according to claim 1, characterized in that: The wireless power transmitting circuit includes a direct current power supply, a high frequency inverter and a primary side compensation circuit, and the wireless power receiving circuit includes a secondary side compensation circuit, a rectifying and filtering circuit and a power load.

3. The power and information parallel transmission system according to claim 2, characterized in that: The primary side compensation circuit, the primary side relay compensation circuit, the secondary side compensation circuit and the secondary side relay compensation circuit all adopt SS type compensation.

4. The power and information parallel transmission system according to any one of claims 1 to 3, characterized in that: The primary-side relay compensation circuit is added with the primary-side relay series LC circuit, and the secondary-side relay compensation circuit is added with the secondary-side relay series LC circuit.

5. The power and information parallel transmission system according to claim 4, characterized in that: A primary-side wave-blocking capacitor is provided between the first switching circuit and the primary-side relay series LC circuit, and a secondary-side wave-blocking capacitor is provided between the second switching circuit and the secondary-side relay series LC circuit.

6. The power and information parallel transmission system according to claim 5, characterized in that: The system resonance condition meets: as well as in: ω p is the angular frequency of the power transmission channel, L1 is the self-inductance of the primary power coil, L2 is the self-inductance of the primary relay coil, L3 is the self-inductance of the secondary relay coil, L4 is the self-inductance of the secondary power coil, C1 is the primary compensation capacitor value connected in series with the primary power coil, C2 is the primary relay compensation capacitor value, C3 is the secondary relay compensation capacitor value, C4 is the secondary compensation capacitor value connected in series with the secondary power coil, L s1 is the inductance value of the primary relay series LC circuit, C s1 is the capacitance value of the primary relay series LC circuit, L s2 is the inductance value of the secondary-side relay series LC circuit, C s2 is the capacitance value of the secondary side relay series LC circuit.

7. The power and information parallel transmission system according to claim 1 or 6, characterized in that: The primary power coil, primary relay coil, secondary power coil and secondary relay coil are designed with a symmetrical coupling structure and meet L1 = L4, L2 = L3, M 12 =M 34 and M 13 =M 24 ,in: L1 is the self-inductance of the primary power coil, L2 is the self-inductance of the primary relay coil, L3 is the self-inductance of the secondary relay coil, L4 is the self-inductance of the secondary power coil, M 12 is the mutual inductance between the primary power coil and the primary relay coil, M 34 is the mutual inductance between the secondary power coil and the secondary relay coil, M 13 is the mutual inductance between the primary power coil and the secondary relay coil, M 24 is the mutual inductance between the primary relay coil and the secondary power coil. All the above parameters are obtained in an underwater environment.

8. The power and information parallel transmission system according to claim 6, characterized in that: The primary side wave blocking capacitor and the secondary side wave blocking capacitor satisfy: Where: s is the angular frequency of the information transmission channel, C ss1 is the primary side wave blocking capacitor value, C ss2 is the secondary side wave blocking capacitor value.

9. The underwater application parameter design method of the electric energy and information parallel transmission system according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: Set the system output power, transmission distance and resonant frequency of the power transmission channel according to the system's underwater application scenario working indicators; S2: Set the system power frequency to satisfy the condition that the power transmission channel voltage gain = 1; S3: Determine the size of the coupling mechanism and the number of coil turns according to the installation space of the system's underwater application scenario; S4: Determine the self-inductance of each coil and the mutual inductance between them through finite element simulation and circuit simulation; S5: determining the capacitance value of each compensation capacitor according to the resonance condition; S6: setting the resonant frequency of the information transmission channel according to the underwater application scenario of the system, so as to satisfy the condition that the ratio of the system power frequency to the resonant frequency of the information transmission channel approaches 0; S7: determining the inductance value in the primary-side relay series LC circuit and the inductance value in the secondary-side relay series LC circuit according to the voltage gain of the information transmission channel; S8: Determine the capacitance value in the primary-side relay series LC circuit, the capacitance value in the secondary-side relay series LC circuit, the primary-side wave-blocking capacitance value, and the secondary-side wave-blocking capacitance value according to the resonance condition; S9: Output all system parameters.

10. The underwater application parameter design method of the electric energy and information parallel transmission system according to claim 9 is characterized in that: When determining the voltage gain of the power transmission channel and the voltage gain of the information transmission channel, the eddy current loss equivalent resistance of each coil in the underwater environment is taken into account in the corresponding equivalent circuit.

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