A self-synchronous tuning very low frequency communication system and switch switching method

Abstract

The invention discloses a self-synchronous tuning very low frequency communication system and a switch switching method, wherein the system comprises: an exciter, a transmitter, a transformer, a self-synchronous tuning network, a fixed tuning network and a VLF antenna connected in sequence; wherein the fixed tuning network comprises at least one group of coarse tuning coils and fine tuning coils; the self-synchronous tuning network comprises a current sensor, a voltage sensor, a coupled inductor module, a phase detection unit, a tuning control unit and a synchronous control switch module on a main loop; the synchronous control switch module comprises at least one group of synchronous switch devices and a corresponding switch drive; the current sensor and the voltage sensor are used to detect the electrical signal of the VLF antenna in real time and transmit it to the phase detection unit, the obtained phase detection result is input into the tuning control unit, and then the tuning control unit outputs a control pulse synchronized with the signal and transmits it to the switch drive, and the action of the corresponding synchronous switch device is controlled by the switch drive.

Description

Technical Field

[0001] The present invention relates to the field of very low frequency communication systems, and in particular to, but not limited to, a self-synchronous tuning very low frequency communication system and a switch switching method. Background Art

[0002] The very low frequency communication transmitting antenna is a high-Q electrically small antenna (ESA), with limited working bandwidth and very low communication rate. An effective way to increase the communication bandwidth without reducing efficiency is to synchronously tune the antenna to the instantaneous frequency. There is a tuning network between the typical VLF (Very Low Frequency) transmitter and the antenna, the main purpose of which is to offset the high capacitive reactance of the VLF electrically small antenna by inserting an inductor in series. The traditional tuning network is mainly composed of coarse tuning coils, fine tuning coils, etc., and is tuned by pre-fixing the frequency point and fixed inductance.

[0003] There are still several difficulties in the traditional very low frequency synchronous tuning system that need to be improved: 1) The use of MSK (Minimum Shift Keying) code elements to control the switch is not convenient for controlling the synchronization error; 2) The tailing effect of electronic switches such as IGBT (Insulated Gate Bipolar Transistor) causes losses; 3) Harmonic interference caused by switch arcing. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a self-synchronous tuning very low frequency communication system and method, which can break through the limitation of ESA high Q on the bandwidth of the antenna feed system, realize self-synchronous tuning of the very low frequency communication system, and effectively reduce the synchronization error and improve the synchronization control accuracy.

[0005] The technical solution of the embodiment of the present invention is achieved as follows:

[0006] In a first aspect, an embodiment of the present invention provides a self-synchronous tuning very low frequency communication system, comprising: an exciter, a transmitter, a transformer, a self-synchronous tuning network, a fixed tuning network and a VLF antenna connected in sequence; wherein the fixed tuning network comprises at least one group of coarse tuning coils and fine tuning coils; the self-synchronous tuning network comprises a current sensor, a voltage sensor, a coupled inductor module, and a phase detection unit, a tuning control unit and a synchronous control switch module on a main loop; the synchronous control switch module comprises at least one group of synchronous switch devices and corresponding switch drives; the current sensor and the voltage sensor are used to detect the electrical signal of the VLF antenna in real time and transmit it to the phase detection unit, and the obtained phase detection result is input into the tuning control unit, and then the tuning control unit outputs a control pulse synchronized with the signal and transmits it to the switch drive, and the action of the corresponding synchronous switch device is controlled by the switch drive.

[0007] In some possible embodiments, the coupled inductor module is a single coupled inductor or a coupled inductor matrix composed of multiple coupled inductors connected in series; each of the coupled inductors includes a primary coil and a secondary coil arranged coaxially and a coupling coefficient of 1, the primary coil is connected in series to the antenna feed system, and the secondary coil and each group of the synchronous switch devices form a coupling loop.

[0008] In some possible embodiments, each group of the synchronous switch devices includes two symmetrically installed control switches, allowing full-cycle AC signals to pass through, and the control switches are electronic switches, including IGBT switches or MOSFET switches.

[0009] In some possible embodiments, when each group of the synchronous switch devices includes two electronic switches, the emitters of the two electronic switches are connected, and the collectors are respectively connected to two ends of the secondary coil in the coupled inductor.

[0010] In a second aspect, an embodiment of the present invention provides a switch switching method, which is applied to the self-synchronous tuning very low frequency communication system described in the first aspect, and the method includes:

[0011] Receive antenna electrical signals collected by voltage sensors and current sensors; perform phase detection on the antenna electrical signals through a phase detection unit; determine whether the antenna feed system is inductive or capacitive based on the phase detection result and a preset threshold, and preset corresponding switching instructions; when it is determined that the antenna current passes through zero, send the switching instruction to the switch drive.

[0012] In some possible embodiments, the determining whether the antenna feed system is inductive or capacitive based on the phase detection result and the preset threshold, and presetting the corresponding switching instruction, include: when the actual phase detected within a single carrier period satisfies the preset threshold, continuing the phase detection; when the actual phase does not satisfy the preset threshold, determining whether the antenna feed system is inductive or capacitive based on the positive or negative value of the actual phase; when the antenna feed system is inductive, presetting a switch-on instruction; when the antenna feed system is capacitive, presetting a switch-off instruction.

[0013] In some possible embodiments, when it is determined that the antenna current passes through zero, the switching instruction is sent to the switch driver, including: when the antenna feed system is inductive and the antenna current is determined to pass through zero, the switch conduction instruction is sent to the switch driver to turn on the synchronous switch device; when the antenna feed system is capacitive and the antenna current is determined to pass through zero, the switch disconnection instruction is sent to the switch driver to disconnect the synchronous switch device.

[0014] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0015] In an embodiment of the present invention, a self-synchronous tuning network is added on the basis of a traditional synchronous tuning network mainly composed of a coarse tuning coil and a fine tuning coil, and is located between the coarse tuning coil and the transformer. Different from the traditional synchronous tuning network (Synchronous Transmission Network, STN), the VLF electric small antenna self-synchronous tuning network provided by the present invention can break through the limitation of ESA high Q on the bandwidth of the antenna feed system. The network does not require MSK code element control, and controls the inductance of the access antenna feed system based on the phase detection result within a single carrier cycle. At the same time, the zero current carrier switching strategy is adopted to reduce the loss caused by the tailing effect of the electronic switch and reduce the harmonic interference caused by the switch arcing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0017] Figure 1 A structural block diagram of a self-synchronous tuning very low frequency communication system provided by an embodiment of the present invention;

[0018] Figure 2 A system architecture diagram of a self-synchronous tuning very low frequency communication system provided by an embodiment of the present invention;

[0019] Figure 3 An extended architecture diagram of a self-synchronous tuning very low frequency communication system provided by an embodiment of the present invention;

[0020] Figure 4 A schematic diagram of an electronic switch synchronous control matrix provided by an embodiment of the present invention;

[0021] Figure 5 A schematic diagram of a flow chart of a switch switching method provided in an embodiment of the present invention;

[0022] Figure 6 A logic flow chart of the electronic switch switching process provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0025] It should be pointed out that the terms "first\second\third" involved in the embodiments of the present invention are only used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of the present invention described here can be implemented in an order other than that illustrated or described here.

[0026] Those skilled in the art will appreciate that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art in the field to which the embodiments of the present invention belong. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as here.

[0027] VLF (Very Low Frequency) electromagnetic waves can penetrate into deeper areas of the sea and are widely used in geological / seabed exploration, underwater communications and navigation.

[0028] MSK is a modulation technique that changes the carrier frequency to transmit information, that is, a special continuous phase frequency shift keying.

[0029] Figure 1 A self-synchronous tuning very low frequency communication system is provided in an embodiment of the present invention, such as Figure 1 As shown, the system includes an exciter 11, a transmitter 12, a transformer 13, a self-synchronous tuning network 14, a fixed tuning network 15 and a VLF antenna 16 connected in sequence;

[0030] The fixed tuning network 15 includes at least one group of coarse tuning coils and fine tuning coils; the self-synchronous tuning network 14 includes a current sensor 141, a voltage sensor 142, a coupled inductor module 143, a phase detection unit 144, a tuning control unit 145 and a synchronous control switch module 146 on the main circuit; the synchronous control switch module 146 includes at least one group of synchronous switch devices 61 and corresponding switch drivers 62;

[0031] The current sensor 141 and the voltage sensor 142 are used to detect the electrical signal of the VLF antenna 16 in real time and transmit it to the phase detection unit 144. The obtained phase detection result is input into the tuning control unit 145, and then the tuning control unit 145 outputs a control pulse synchronized with the signal and transmits it to the switch driver 62. The action of the corresponding synchronous switch device 61 is controlled by the switch driver 62.

[0032] In an embodiment of the present invention, a self-synchronous tuning network is added on the basis of a traditional synchronous tuning network mainly composed of a coarse tuning coil and a fine tuning coil, and is located between the coarse tuning coil and the transformer. Different from the traditional synchronous tuning network, the VLF electric small antenna self-synchronous tuning network provided by the present invention can break through the limitation of the ESA high Q on the bandwidth of the antenna feed system. The network does not require MSK code element control, and controls the inductance of the access antenna feed system based on the phase detection result within a single carrier cycle. At the same time, the zero current carrier switching strategy is adopted to reduce the loss caused by the tailing effect of electronic switches such as IGBTs, and reduce the harmonic interference caused by switch arcing.

[0033] In some possible embodiments, the coupled inductor module is a single coupled inductor or a coupled inductor matrix composed of multiple coupled inductors connected in series; each of the coupled inductors includes a primary coil and a secondary coil arranged coaxially and a coupling coefficient of 1, the primary coil is connected in series to the antenna feed system, and the secondary coil and each group of the synchronous switch devices form a coupling loop.

[0034] Here, the antenna feed system refers to a system in which the antenna radiates electromagnetic waves into the surrounding space. It mainly includes two categories: antenna and feeder system.

[0035] The embodiment of the present invention adds a self-synchronous tuning network on the basis of the traditional tuning network, which is located between the coarse tuning coil and the transformer and consists of a single coupled inductor or multiple coupled inductors connected in series. The primary coil in each coupled inductor is connected in series to the main loop, and the secondary coil and a group of synchronous switching devices form a coupling loop. By using coupled inductors, the coupling coefficient is increased to 1, and the magnetic saturation phenomenon and hysteresis loss are reduced.

[0036] It is worth noting that, since each secondary coil corresponds to a group of synchronous switch devices, the number of coupled inductors connected in series in the coupled inductor module is consistent with the number of groups of synchronous switch devices.

[0037] Taking a single coupled inductor as an example, the system architecture diagram of the self-synchronous tuning very low frequency communication system provided by the present invention is as follows: Figure 2 As shown, it includes an exciter 21, a transmitter 22, a transformer 23, a self-synchronous tuning network 24, a fixed tuning network consisting of a coarse tuning coil 251 and a fine tuning coil 252, and a VLF antenna 26, wherein the self-synchronous tuning network 24 includes a voltage sensor 241, a current sensor 242, a single coupled inductor 243, a phase detection unit 244, a tuning control unit 245, and an electronic switch driver 246 (equivalent to Figure 1 The switch drive 62 in the figure) and a synchronous switch device composed of two electronic switches (G1 and G2 in the figure) (equivalent to Figure 1 The synchronous switching device 61 in the embodiment of the present invention.

[0038] Taking a coupled inductor array composed of two coupled inductors as an example, the system architecture diagram of the self-synchronous tuning very low frequency communication system provided by the present invention is as follows: Figure 3 As shown, it includes an exciter 31, a transmitter 32, a transformer 33, a self-synchronous tuning network 34, a fixed tuning network 35 consisting of two coarse tuning coils and two fine tuning coils, and a VLF antenna 36, ​​wherein the self-synchronous tuning network 34 includes a voltage sensor 341, a current sensor 342, a coupled inductor array 343, a phase detection unit 344, a tuning control unit 345, and two electronic switch drivers 346 (equivalent to Figure 1 A group of synchronous switch devices are controlled by the switch drive 62 in each synchronous switch device, each synchronous switch device (equivalent to Figure 1 The synchronous switch device 61 in the figure includes two electronic switches (G1 and G2 in the figure) and is connected to both ends of a secondary coil of a coupled inductor.

[0039] It can be seen that the coupled inductor module in the system can be composed of a single coupled inductor or a coupled inductor array, which is suitable for synchronous tuning of multiple frequency points and has strong system scalability. At the same time, the coupled inductor structure is similar to a transformer and has a high degree of isolation, which can improve the safety of the system.

[0040] In some possible embodiments, each group of the synchronous switch devices includes two symmetrically installed control switches, allowing full-cycle AC signals to pass through, and the control switches are electronic switches, including IGBT switches or MOSFET switches.

[0041] Here, an electronic switch is an electronic component used to control the on and off of current, and can control the current through electronic signals. There are many types of electronic switches, including but not limited to IGBT switches, MOSFET switches, bipolar transistors BJT, etc. Among them, IGBT is a minority carrier device with high input impedance and strong current carrying capacity. From the perspective of circuit designers, IGBT has the input characteristics of MOS devices and the current output capacity of bipolar devices. It is a voltage-controlled bipolar device.

[0042] MOSFET switches have low switching losses. As an electronic switch, MOSFET mainly utilizes its conductivity under the control of gate-source voltage. By changing the gate-source voltage VGS, the element is switched between short-circuit (ON) and open-circuit (OFF) states, thereby achieving efficient voltage control and power management.

[0043] A synchronous switching device can be composed of an IGBT switch or a MOSFET switch, which is suitable for fast switching.

[0044] In some possible embodiments, when each group of the synchronous switch devices includes two electronic switches, the emitters of the two electronic switches are connected, and the collectors are respectively connected to two ends of the secondary coil in the coupled inductor.

[0045] For example, Figure 4 As shown, the emitters of the two electronic switches are connected, and the collectors are connected to the two ends of the secondary coil of the coupled inductor, and the primary coil of the coupled inductor is connected in series to the antenna feed system. The synchronous switch device is not limited to two electronic switches, and can be expanded on this basis according to actual needs to form a synchronous control array. In this case, it is necessary to consider the voltage or current balancing of the control array. In this way, the coupled inductor and the switch state switching speed are fast, can withstand high voltage and high current, and adapt to high-power very low frequency signals.

[0046] Figure 5 A schematic diagram of a flow chart of a switch switching method provided by an embodiment of the present invention, such as Figure 5As shown, the method is applied to the self-synchronous tuning very low frequency communication system provided by the present invention, and the method at least comprises the following steps:

[0047] Step S510: receiving antenna electrical signals collected by the voltage sensor and the current sensor.

[0048] Here, the voltage sensor and the current sensor input the collected antenna electrical signal into the phase detection unit.

[0049] Step S520: performing phase detection on the antenna electrical signal by a phase detection unit.

[0050] Here, the phase result is compared with the set phase threshold. If the threshold condition is met, the phase detection continues. Otherwise, the positive or negative phase difference is judged to determine whether the antenna feed system is inductive or capacitive.

[0051] Step S530: determine whether the antenna feed system is inductive or capacitive based on the phase detection result and the preset threshold, and preset a corresponding switching instruction.

[0052] Here, the phase detection result obtained in the previous step is compared with the preset phase threshold. If the threshold condition is met, the phase detection continues. Otherwise, the positive or negative phase difference is judged to determine whether the antenna feed system is inductive or capacitive.

[0053] It is worth noting that the switching of the synchronization control switch in the self-synchronous tuning very low frequency communication system provided by the present invention does not need to be controlled by the MSK code element signal, but the synchronization control switch is controlled according to the phase detection result within a single carrier cycle, and the final manifestation is that the conduction or disconnection of the synchronization control switch is still quickly switched following the MSK carrier frequency.

[0054] Step S540: When it is determined that the antenna current passes through zero, the switching instruction is sent to the switch driver.

[0055] Here, since the primary coil is connected in series in the main circuit and carries alternating currents ranging from several amperes to hundreds of amperes, when the switch occurs at the current peak or trough, it will cause switching noise or even strong pulse discharge, affecting the performance and safety of the system. Here, we draw on the idea of ​​soft switching technology and adopt a zero-current carrier switching strategy: the voltage sensor and the current sensor input the collected antenna electrical signal into the phase detection unit, and the phase result is compared with the set phase threshold. If the threshold condition is met, the phase detection continues. Otherwise, the positive or negative phase difference is judged to determine whether the antenna feed system is inductive or capacitive, and the electronic switch is turned on or off accordingly. After the above judgment is completed, it is determined whether the antenna current is zero, and the previously preset switching instruction is sent when the current is zero.

[0056] Under the control of the zero current carrier switching strategy, the current of the synchronous control switch is zero before it is turned off, and no loss or noise is generated when it is turned off. When the zero current is turned on, the inductor in series with the synchronous control switch can slow down the rate of current rise after the switch is turned on, reducing the turn-on loss.

[0057] In an embodiment of the present invention, based on a very low frequency communication self-synchronous tuning system structure, a switching method is proposed that uses the phase detection result within a single carrier cycle to control the synchronous control switch, without the need for MSK code element control, thereby reducing the error of the synchronous control; at the same time, a zero current carrier switching strategy is adopted to reduce the loss caused by the tailing effect of the electronic switch and reduce the harmonic interference caused by the switch arcing.

[0058] In some possible embodiments, the above step S530 is further implemented as the following steps: when the actual phase detected within a single carrier period meets the preset threshold, continue phase detection; when the actual phase does not meet the preset threshold, determine whether the antenna feed system is inductive or capacitive based on the positive or negative value of the actual phase; when the antenna feed system is inductive, preset a switch on instruction; when the antenna feed system is capacitive, preset a switch off instruction.

[0059] In some possible embodiments, the above step S540 is further implemented as the following steps: when the antenna feed system is inductive and it is determined that the antenna current passes through zero, the switch-on instruction is sent to the switch driver to turn on the synchronous switch device; when the antenna feed system is capacitive and it is determined that the antenna current passes through zero, the switch-off instruction is sent to the switch driver to turn off the synchronous switch device.

[0060] Here, the present invention adopts a zero current carrier switching strategy, and the overall switch switching process is as follows: Figure 6 As shown, it includes: S1, phase detection; S2, judging whether the phase meets the preset threshold, if so, repeating step S1, if not, continuing to execute step S3; S3, inductive / capacitive judgment of the antenna feed system; after the above judgment, executing step S4 to judge whether the current passes through zero; S5, sending a switching instruction; S6, driving the electronic switch to turn on or off.

[0061] The present invention proposes a very low frequency synchronous tuning system based on coupled inductors and a switching method thereof, which have the following main advantages: 1) no MSK symbol control is required, and the phase detection result within a single carrier cycle is used to control the synchronous control switch; 2) coupled inductors are used to improve the coupling coefficient, so that the coupling coefficient is 1, and magnetic saturation and hysteresis loss are reduced; 3) the scalability is strong, and the coupled inductor can be composed of a single coupled inductor or a coupled inductor matrix, etc., which is suitable for synchronous tuning of multiple frequency points; the switch matrix can be composed of electronic switches such as IGBT or MOSFET, which is suitable for fast switching; 4) the coupled inductor and the switch state switching speed are fast, can withstand high voltage and large current, and adapt to high-power very low frequency signals; 5) the zero current carrier switching strategy is adopted, which can reduce the loss caused by the tailing effect of the electronic switch and reduce the harmonic interference caused by the switch arcing; 6) the coupled inductor structure is similar to a transformer, has a high isolation, and can improve the safety of the system.

[0062] Based on the same technical concept, an embodiment of the present invention provides an electronic device for implementing the switch switching method described in the above method embodiment. The electronic device includes a memory and a processor, the memory stores a computer program that can be run on the processor, and the processor implements the steps in any of the switch switching methods described in the embodiments of the present invention when executing the program.

[0063] Correspondingly, an embodiment of the present invention provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the steps in the switch switching method described in any of the above embodiments are implemented. Correspondingly, an embodiment of the present invention also provides a computer program product, and when the computer program product is executed by a processor of an electronic device, it is used to implement the steps in the switch switching method described in any of the above embodiments.

[0064] It should be noted that the description of the above storage medium and device embodiments is similar to the description of the above method embodiments, and has similar beneficial effects as the method embodiments. For technical details not disclosed in the storage medium and device embodiments of the present invention, please refer to the description of the method embodiments of the present invention for understanding.

[0065] It should be noted that in the embodiment of the present invention, if the above-mentioned self-switch switching method is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present invention can be essentially or partly reflected in the form of a software product that contributes to the relevant technology. The computer software product is stored in a storage medium, including several instructions for enabling an electronic device to execute all or part of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a U disk, a mobile hard disk, a read-only memory (ROM), a magnetic disk or an optical disk. In this way, the embodiment of the present invention is not limited to any specific combination of hardware and software.

[0066] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in various embodiments of the present invention, the size of the serial number of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention. The serial numbers of the above-mentioned embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments.

[0067] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0068] The methods disclosed in several method embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new method embodiments. The features disclosed in several method embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new method embodiments.

[0069] The above is only an embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A self-synchronous tuning very low frequency communication system, characterized in that: It includes an exciter, a transmitter, a transformer, a self-synchronous tuning network, a fixed tuning network and a VLF antenna connected in sequence; wherein the fixed tuning network includes at least one group of coarse tuning coils and fine tuning coils; the self-synchronous tuning network includes a current sensor, a voltage sensor, a coupled inductor module, a phase detection unit, a tuning control unit and a synchronous control switch module on the main loop; the synchronous control switch module includes at least one group of synchronous switch devices and corresponding switch drivers; The current sensor and the voltage sensor are used to detect the electrical signal of the VLF antenna in real time and transmit it to the phase detection unit. The obtained phase detection result is input into the tuning control unit, and then the tuning control unit outputs a control pulse synchronized with the signal and transmits it to the switch drive, and the action of the corresponding synchronous switch device is controlled by the switch drive.

2. The system according to claim 1, characterized in that The coupled inductor module is a single coupled inductor or a coupled inductor matrix composed of multiple coupled inductors connected in series; each of the coupled inductors includes a primary coil and a secondary coil arranged coaxially and a coupling coefficient of 1, the primary coil is connected in series to the antenna feed system, and the secondary coil and each group of the synchronous switch devices form a coupling loop.

3. The system according to claim 1, characterized in that Each group of the synchronous switch devices includes two symmetrically installed control switches, allowing full-cycle AC signals to pass through. The control switches are electronic switches, including insulated gate bipolar transistor IGBT switches or metal oxide semiconductor field effect transistor MOSFET switches.

4. The system according to claim 3, characterized in that In the case where each group of the synchronous switch devices includes two electronic switches, the emitters of the two electronic switches are connected, and the collectors are respectively connected to the two ends of the secondary coil in the coupled inductor.

5. A switch switching method, characterized in that: Applied to the self-synchronous tuning very low frequency communication system according to any one of claims 1 to 4, the method comprises: Receive antenna electrical signals collected by voltage sensors and current sensors; Performing phase detection on the antenna electrical signal by a phase detection unit; Based on the phase detection result and the preset threshold, it is determined whether the antenna feed system is inductive or capacitive, and a corresponding switching instruction is preset; When it is determined that the antenna current passes through zero, the switching instruction is sent to the switch driver.

6. The method according to claim 5, characterized in that The determining whether the antenna feed system is inductive or capacitive based on the phase detection result and the preset threshold value, and presetting the corresponding switching instruction, includes: When the actual phase detected within the single carrier period meets the preset threshold, continue phase detection; When the actual phase does not meet the preset threshold, determining whether the antenna feed system is inductive or capacitive based on the positive or negative value of the actual phase; When the antenna feed system is inductive, a switch-on instruction is preset; When the antenna feed system is capacitive, a switch disconnect instruction is preset.

7. The method according to claim 6, characterized in that When it is determined that the antenna current passes through zero, sending the switching instruction to the switch driver comprises: When the antenna feed system is inductive and it is determined that the antenna current is zero-crossing, sending the switch-on instruction to the switch driver to turn on the synchronous switch device; When the antenna feed system is capacitive and it is determined that the antenna current passes through zero, the switch disconnection instruction is sent to the switch driver to disconnect the synchronous switch device.

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