Power electronic secondary power supplies and their control methods and control systems

Abstract

This invention discloses a power electronic secondary power supply and its control method and control system, realizing the integrated auxiliary power supply and communication functions of a large-scale AC-DC / DC-AC converter, while improving the voltage stability of the auxiliary power supply under communication conditions. The power electronic secondary power supply includes a rectifier bridge module, a single-stage BOOST module, a three-port LLC converter, and an LC coupling circuit. Its communication method is resonant voltage communication. The power electronic secondary power supply injects a high-frequency resonant voltage into the LC coupling circuit, and through this resonant voltage, injects a communication signal into the power grid, realizing communication of the power electronic converter. This invention's ultra-high frequency power-to-signal simultaneous transmission method for a power electronic secondary power supply combines AC microgrid auxiliary power supply with communication functions. Furthermore, by spreading the spectrum, the original symbols are expanded to high-frequency symbols, thereby achieving equal power transmission over the average time during information transmission and stronger output voltage stability.

Description

Technical Field

[0001] This invention relates to the fields of power electronics and communication technology, and in particular to a power electronic secondary power supply and its control method and control system. Background Technology

[0002] As the proportion of renewable energy in the power system continues to increase, the phenomenon of power curtailment caused by the lack of scientific planning for large-scale grid connection of new energy sources is becoming increasingly prominent. Based on this, intelligent energy coordination management of DC microgrids is gradually becoming an important development direction for the efficient utilization of new energy sources, which poses new challenges to the system's information interaction architecture and dynamic control capabilities.

[0003] The common communication methods used in intelligent energy coordination systems of DC microgrids can be divided into two main categories: wired communication and wireless communication. Wireless communication, limited by complex application scenarios, suffers from issues related to communication distance, security, and quality. Wired communication methods such as RS-485 and CAN have limited transmission distances and require additional communication lines, while power line carrier communication requires additional auxiliary equipment and is generally more expensive. Therefore, existing communication methods still have their limitations in meeting the communication requirements of intelligent energy coordination systems in DC microgrids. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a power electronic secondary power supply and its control method and control system to address the shortcomings of existing technologies, so as to realize the simultaneous transmission of power and information; and effectively solve the communication limitation problem in complex environments and long-distance AC microgrids.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a power electronic secondary power supply, including a rectifier bridge module, a BOOST module, a three-port LLC converter, and an LC coupling circuit; the rectifier module is connected to the BOOST module, and the BOOST module is connected to the primary side of the transformer in the LLC converter; the LC coupling circuit is connected to the tertiary side of the transformer in the LLC converter, and is connected in parallel with the rectifier module and the BOOST module; the LLC converter includes a resonant inductor, a resonant capacitor, and a transformer, the resonant inductor is connected to the resonant capacitor, the resonant capacitor is connected to the positive terminal of the primary side and one end of the magnetizing inductor; the negative terminal of the primary side and the other end of the magnetizing inductor are connected to the power grid; the secondary side of the transformer includes a positive terminal, a negative terminal, and a center tap; the positive terminal of the secondary side is connected to the anode of a first fast recovery diode, the negative terminal of the secondary side is connected to the anode of a second fast recovery diode, and the center tap of the secondary side is connected to the negative terminal of the output capacitor.

[0006] This invention enables the PFC-LLC converter to achieve simultaneous transmission of power and signal by reusing the transformer in the auxiliary power supply and adding a third winding thereon.

[0007] The BOOST module includes a first MOSFET, a bus capacitor, and a MOSFET branch connected in parallel; the MOSFET branch includes a second MOSFET and a third MOSFET connected in series; one end of the resonant inductor of the LLC converter is connected between the second MOSFET and the third MOSFET.

[0008] The LLC converter includes a coupling inductor and a coupling capacitor; one end of the coupling inductor is connected to the positive terminal of the third side of the three-port LLC converter, and the other end is connected to one end of the coupling capacitor, the other end of which is connected to the power grid.

[0009] The output voltage of the LLC converter is kV bus V bus is the input voltage of the LLC converter, and k is the variable gain.

[0010] As an inventive concept, the present invention also provides a control method for the above-mentioned power electronic secondary power supply, which includes the following steps:

[0011] When information bit 1 needs to be transmitted, information bit 1 is extended to 0101. In the current cycle, chip 0 is transmitted first, and the LLC converter stops working. In the next cycle, chip 1 is transmitted, injecting a one-cycle high-frequency sine wave into the power grid. This process continues for the next two cycles of chip 0 and chip 1 transmission until information bit 1 transmission is completed.

[0012] When information bit 0 needs to be transmitted, information bit 0 is extended to 0011. In two consecutive cycles, two chips 0 are transmitted sequentially. During these two cycles, the LLC converter does not work. In the next two consecutive cycles, two chips 1 are transmitted sequentially. The LLC converter works during these two consecutive cycles, injecting two cycles of high-frequency sine waves into the power grid.

[0013] In this invention, the output voltage of the LLC converter is subtracted from the output voltage reference value to generate an output voltage error. The output voltage error is then sent to a PI controller to generate an input current reference amplitude. The input voltage of the BOOST module is divided by the BOOST module input voltage amplitude to obtain the input current reference phase. The input current reference amplitude is multiplied by the input current reference phase to generate an input current reference instantaneous value. The input current reference instantaneous value is subtracted from the input current sampling value of the BOOST module, and the difference is sent to the PI controller to obtain the duty cycle of each MOS transistor in the BOOST module.

[0014] As an inventive concept, the present invention also provides a control system for a power electronic secondary power supply, including a memory, a processor, and a computer program stored in the memory; the processor executes the computer program to implement the steps of the above method.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. This invention achieves the effect of simultaneous transmission of power and signal by reusing the transformer in the auxiliary power supply and adding a third winding thereon.

[0017] 2. Due to the use of switching frequency for communication, the communication frequency of this invention is increased by 5-10 times compared to the original energy-communication module that uses current loop for current feedback to achieve simultaneous energy and communication.

[0018] 3. By changing the outer loop control quantity of the BOOST module from the bus voltage to the output voltage, this invention ensures the stability of the output voltage of the energy and information transmission module over a long time scale when performing energy and information transmission.

[0019] 4. This invention adopts spread spectrum communication, which increases the communication frequency by 4 times and reduces the possibility of communication errors. Secondly, spread spectrum communication also ensures the stability of the LLC converter's transmission power when each information bit is transmitted, thus ensuring the stability of the output voltage of the simultaneous transmission module over a short time scale. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the application scenario of the power electronic secondary power supply according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the power electronic secondary power supply circuit structure according to an embodiment of the present invention;

[0022] Figure 3 The logic diagram for stabilizing the output voltage under load changes, which is the BOOST control used in this invention;

[0023] Figure 4 The control block diagram for simultaneous signal transmission using BOOST-LLC under conventional control;

[0024] Figure 5 Block diagram of direct sequence spread spectrum control for power electronic secondary power supply according to an embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of the output current, output power, and output voltage waveforms when transmitting the same symbols under conventional control as the method proposed in this invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] This embodiment provides a power electronic secondary power supply, which provides auxiliary power to DC-AC converters or AC-DC converters in an AC microgrid while also undertaking communication functions. It includes: a rectifier bridge module, a BOOST module, a three-port LLC converter, and an LC coupling circuit.

[0029] The positive terminal of the rectifier bridge module is connected to one end of the inductor in the subsequent BOOST module, and the negative terminal is connected to the source of MOSFET S1 and the bus capacitor C in the subsequent BOOST module. BUS The negative terminal of the MOSFET S3 in the three-port LLC module and the negative terminal of the primary side of the transformer T1 in the three-port LLC module are connected. The rectifier bridge has four diodes, divided into two groups. The two diodes in each group are connected end-to-end, with this connection point connected to the power grid. The two diode groups are then connected end-to-end to form the positive terminal of the rectifier bridge; and end-to-end connections form the negative terminal. These four diodes rectify the AC voltage into a peaked wave, requiring rapid recovery to ensure timely cutoff and prevent current reversal.

[0030] The BOOST module includes a BOOST inductor L, a fast recovery diode D1, a MOSFET S1, and a bus capacitor C. BUS One end of the BOOST inductor L is connected to the anode of the fast recovery diode D1 and the drain of the MOSFET S1; the other end is connected to the anode of the rectifier bridge module. The drain of the MOSFET S1 is connected to the anode of the fast recovery diode D1 and one end of the BOOST inductor L; its source is connected to the cathode of the rectifier bridge and the bus capacitor C. BUS The negative terminal of the MOSFET S3 in the three-port LLC module is connected to the source terminal of the MOSFET S3 and the negative terminal of the primary side of the transformer T1 in the three-port LLC module. The positive terminal of the fast recovery diode D1 is connected to the drain terminal of the MOSFET S1 and one end of the BOOST inductor L; its negative terminal is connected to the bus capacitor C. BUS In the positive terminal and three-port LLC module, the drain of MOSFET S2 is connected. The bus capacitor C... BUSThe positive terminal is connected to the negative terminal of diode D1 and the drain of MOSFET S2 in the three-port LLC module; its negative terminal is connected to the negative terminal of the rectifier bridge, the source of MOSFET S1, the source of MOSFET S3 in the three-port LLC module, and the negative terminal of the primary side of transformer T1 in the three-port LLC module. When MOSFET S1 is turned on, the BOOST inductor L absorbs the energy transferred from the rectifier bridge, causing the inductor current to rise; simultaneously, the fast recovery diode D1 is reverse-biased to prevent the bus capacitor C from being turned off. BUS Reverse energy transfer occurs. When MOSFET S1 is turned off, the inductor releases its stored energy, causing fast recovery diode D1 to conduct, supplying power to the bus capacitor C. BUS The charging process stabilizes the bus voltage.

[0031] The three-port LLC module includes MOSFET S2, MOSFET S3, and resonant inductor L. r Resonant capacitor C r Transformer T1, Fast recovery diode D2, Fast recovery diode D3, Output capacitor C o The drain of the MOS transistor S2 is connected to the negative terminal of the fast recovery diode D1 in the BOOST module and the bus capacitor C. BUS The positive terminal is connected; its source terminal is connected to MOSFET S3 and resonant inductor L. r One end is connected. The drain of MOSFET S3 is connected to the source of MOSFET S2 and the resonant inductor L. r One end is connected; its source is connected to the primary side negative terminal of transformer T1, the negative terminal of the rectifier bridge module, the source of MOS transistor S1 in the BOOST module, and the bus capacitor C. BUS The negative terminals are connected. The resonant inductor L... r One end is connected to the source of MOSFET S2 and the drain of MOSFET S3; the other end is connected to the resonant capacitor C. r One end is connected. Resonant capacitor C r One end is connected to the resonant inductor L r One end is connected; the other end is connected to the positive terminal of the primary side of transformer T1. The positive terminal of the primary side of transformer T1 is connected to the resonant capacitor C. r One end is connected; its primary side negative terminal is connected to the negative terminal of the rectifier bridge module, the source of the MOS transistor S1 in the BOOST module, and the bus capacitor C. BUS The negative terminal is connected to the source of MOSFET S3; its secondary side has three interfaces: positive, negative, and center tap; its secondary positive terminal is connected to the positive terminal of fast recovery diode D2; its secondary negative terminal is connected to the positive terminal of fast recovery diode D3; the secondary center tap is connected to the output capacitor C. o The negative terminal and the output negative terminal are connected; its tertiary positive terminal is connected to the coupling inductor L in the LC coupling circuit. s One end is connected; its tertiary negative terminal is connected to the power grid. The positive terminal of the fast recovery diode D2 is connected to the positive terminal of the secondary side of transformer T1; its negative terminal is connected to the output capacitor C.o The positive terminal of the fast recovery diode D3, the negative terminal of the fast recovery diode D3, and the output positive terminal are connected together. The positive terminal of the fast recovery diode D3 is connected to the negative terminal of the secondary side of transformer T1; its negative terminal is connected to the output capacitor C. o The positive terminal, the negative terminal of the fast recovery diode D2, and the output positive terminal are connected together. The output capacitor C... o The positive terminal is connected to the negative terminal of fast recovery diode D2, the positive terminal of fast recovery diode D3, and the output positive terminal; its negative terminal is connected to the center tap of the secondary side of transformer T1 and the output negative terminal. Three-port LLC MOSFETs S2 and S3 conduct complementaryly to form a square wave voltage, which is generated by the resonant inductor L. r Resonant capacitor C r Magnetizing inductance L in transformer T1 m Under the action of the transformer, a sinusoidal current is formed. This current is transmitted to the output terminal through transformer T1. After passing through the secondary side, it is rectified by half-wave and filtered by the output capacitor to form a stable DC output current. At the same time, a square wave voltage is generated on the tertiary side.

[0032] The LC coupling circuit consists of a coupling inductor L s Coupling capacitor C s Composition. Coupled inductor L s One end is connected to the positive terminal of the tertiary side of transformer T1 in the three-port LLC; the other end is connected to the coupling capacitor C. s One end is connected. Coupling capacitor C s One end is coupled to inductor L s One end is connected to the mains; the other end is connected to the power grid. The square wave voltage generated by the tertiary side of transformer T1 passes through the coupling inductor L in the coupling circuit. s With coupling capacitor C s The filter outputs a sinusoidal voltage to the power grid; the 50Hz power frequency voltage in the power grid, due to its low frequency, will be coupled by capacitor C. s This allows for the capture of voltage, thereby decoupling the output voltage from the high voltage in the power grid.

[0033] Example 2

[0034] This embodiment provides a control method for the power electronic secondary power supply described in Embodiment 1 above.

[0035] The power electronic secondary power supply can achieve communication transmission function by injecting high-frequency signals through the switching of MOSFETs S2 and S3 via spread spectrum modulation, which are ultimately reflected in the mains voltage. Specifically:

[0036] In traditional control, the BOOST converter controls the bus voltage to stabilize it and controls the input current to produce a sinusoidal waveform; the LLC converter stabilizes the output voltage at a certain value through frequency conversion. However, in scenarios involving simultaneous information transmission and communication, the LLC converter needs to operate intermittently at a certain frequency to achieve the desired information transmission effect, making it impossible to control the output voltage via the LLC converter. In such cases, the traditional method cannot control the output voltage, potentially leading to voltage overshoot.

[0037] Treating the relationship between the LLC converter's input and output voltages as a variable gain k, the relationship between the LLC input voltage (i.e., the bus voltage) and the LLC output voltage can be derived. If the bus voltage is V... bus The output voltage is kV. bus The output voltage changes as the operating point changes.

[0038] Traditional control methods for BOOST converters, such as Figure 4 As shown, the outer-loop PI controller uses the sampled value and reference value of the bus voltage to calculate the amplitude of the input current reference quantity. The phase of this input current reference quantity is obtained from the input voltage sampling; the input voltage phase is obtained by dividing the input voltage by its amplitude. Multiplying the phase by the amplitude yields the input current reference value. The inner-loop PI controller then calculates the duty cycle of the BOOST controller by combining this reference value with the sampled value. As the principle of the BOOST circuit shows, when the duty cycle of the BOOST controller changes, its input current and output voltage also change accordingly. Therefore, through the dual-loop control of the PI controller, the input current and bus voltage of the BOOST circuit can be controlled. This invention replaces the input reference and feedback quantities of the BOOST converter's outer-loop voltage controller with the output voltage. The output voltage error is generated by subtracting the output voltage from the output voltage reference value. This error is then fed into a PI controller to generate the input current reference amplitude. Compared to traditional control methods, this method bypasses the LLC converter and directly controls the output voltage, reducing output voltage fluctuations caused by changes in the LLC converter's operating point. Other control parameters are similar to traditional control methods (see the specific control block diagram). Figure 5 As shown), the BOOST converter can use its outer loop control to change the input current reference amplitude and increase / decrease the bus voltage V when the load changes. bus This offsets the gain changes in the LLC converter caused by load variations, indirectly keeping the output voltage constant and solving the problem of unstable output voltage of the transmission device when the BOOST converter adopts traditional control.

[0039] When a power supply performs simultaneous power transmission, the primary information transmitter is the LLC converter. When the LLC converter starts up, it transmits a switching frequency signal to the power grid, representing information bit 1; when the LLC converter stops, it does not transmit the switching frequency signal to the power grid, representing information bit 0. For example... Figure 4 As shown, its operation is as follows: When transmitting information bit 1, MOSFETs S2 and S3 are complementaryly turned on, with both having a duty cycle of 50%. Their switching frequency is equal to the resonant inductor L. r Resonant capacitor C r At the resonant frequency, a square wave voltage is generated on transformer T1. This square wave voltage is filtered out of high-frequency components through an LC coupling circuit, retaining only the communication frequency components. This forms a sine wave of the communication frequency in the power grid, thus transmitting information to the grid and simultaneously transferring electrical energy to the output section. When transmitting information bit 0, MOSFETs S2 and S3 are both turned off, preventing the grid from obtaining the high-frequency communication voltage and preventing the output voltage side from receiving energy from the preceding stage. This is the process of energy and information transmission simultaneously using the ASK method in an LLC converter. However, this method has a drawback: when multiple information bits are 0, the output voltage side will be unable to receive energy from the preceding stage for an extended period. The output side can only supply power to the subsequent stage through capacitor energy storage, leading to a voltage drop. Furthermore, due to the voltage drop, if the BOOST feedback is set to the output voltage, it will detect the output voltage drop, further increasing the input current reference amplitude. This increases the input current, causing the bus capacitor voltage to rise, potentially exceeding the capacitor's rated capacity, leading to capacitor damage and threatening user safety.

[0040] like Figure 5As shown: In this embodiment of the invention, information bit 1 is expanded to "0101" and information bit 0 is expanded to "0011". Each piece of expanded data is called a chip, where chip 1 represents LLC operation and chip 0 represents LLC inoperability. When transmitting information bit 1, the converter transmits chip combination 0101. First, chip 0 is transmitted, at which point the periodic converter stops operating, neither transmitting energy to the subsequent stage nor injecting a high-frequency sine wave into the power grid; then chip 1 is transmitted, at which point the periodic converter transmits one cycle of energy to the subsequent stage and injects one cycle of high-frequency sine wave into the power grid; subsequently, chips 0 and 1 are transmitted, thus ending the transmission of information bit 1. When transmitting information bit 0, the converter transmits chip combination 0011. Because two chips are linked together in this information bit, the transmission process is as follows: First, two chips 0 are transmitted, during which the converter does not operate for two cycles, neither transmitting energy to the subsequent stage nor injecting a high-frequency sine wave into the power grid; then, two chips 1 are transmitted, during which the converter operates continuously for two cycles, transmitting energy to the subsequent stage for two cycles, and simultaneously injecting a high-frequency sine wave into the power grid for two cycles. Thus, regardless of whether information bit 1 or information bit 0 is transmitted, one information bit cycle always contains four operating cycles, with the LLC converter operating for two cycles, transmitting the same amount of energy to the subsequent stage, and its energy transmission is not interrupted for extended periods. This solves the potential voltage instability and capacitor voltage exceeding limits that may occur when the LLC converter transmits signals in the ASK mode.

[0041] The specific differences between the communication process in this embodiment of the invention and existing methods are as follows: Figure 6 As shown. Using the original control method, when information bit 1 is transmitted, the current output by the LLC to the capacitor remains continuous, and the output power also remains continuous. However, when information bit 0 is transmitted, the LLC does not output current to the capacitor, nor does it output power, leading to a drop in output voltage. Using the technology proposed in this embodiment, during the transmission of information bit 1 and information bit 0, within four switching cycles, the LLC outputs current to the capacitor and transmits power for two switching cycles each. The transmitted power is the same throughout the four cycles and is uninterrupted; therefore, its output voltage does not drop.

[0042] Example 3

[0043] Embodiment 2 of the present invention provides a control system corresponding to Embodiment 2 above, including a memory, a processor, and a computer program stored in the memory; the processor executes the computer program in the memory to implement the steps of the method of Embodiment 2 above.

[0044] In some implementations, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.

[0045] In other implementations, the processor can be any type of general-purpose processor, such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation here.

[0046] Example 3

[0047] Embodiment 3 of the present invention provides a computer-readable storage medium corresponding to Embodiment 2 above, on which a computer program / instructions are stored. When the computer program / instructions are executed by a processor, they implement the steps of the method of Embodiment 2 above.

[0048] A computer-readable storage medium can be a tangible device that holds and stores instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0049] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0050] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0051] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0052] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0053] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A power electronic secondary power supply, characterized in that, The system includes a rectifier bridge module, a BOOST module, a three-port LLC converter, and an LC coupling circuit. The rectifier module is connected to the BOOST module, and the BOOST module is connected to the primary side of the transformer in the LLC converter. The LC coupling circuit is connected to the tertiary side of the transformer in the LLC converter and is connected in parallel with the rectifier module and the BOOST module. The LLC converter includes a resonant inductor, a resonant capacitor, and a transformer. The resonant inductor is connected to the resonant capacitor, which is connected to the positive terminal of the primary side and one end of the magnetizing inductor. The negative terminal of the primary side and the other end of the magnetizing inductor are connected to the power grid. The secondary side of the transformer includes a positive terminal, a negative terminal, and a center tap. The positive terminal of the secondary side is connected to the anode of a first fast recovery diode, the negative terminal of the secondary side is connected to the anode of a second fast recovery diode, and the center tap of the secondary side is connected to the negative terminal of the output capacitor.

2. The power electronic secondary power supply according to claim 1, characterized in that, The BOOST module includes a first MOSFET, a bus capacitor, and a MOSFET branch connected in parallel; the MOSFET branch includes a second MOSFET and a third MOSFET connected in series; one end of the resonant inductor of the LLC converter is connected between the second MOSFET and the third MOSFET.

3. The power electronic secondary power supply according to claim 1, characterized in that, The LLC converter includes a coupling inductor and a coupling capacitor; one end of the coupling inductor is connected to the positive terminal of the third side of the three-port LLC converter, and the other end is connected to one end of the coupling capacitor, the other end of which is connected to the power grid.

4. The power electronic secondary power supply according to claim 1, characterized in that, The output voltage of the LLC converter is kV bus V bus is the input voltage of the LLC converter, and k is the variable gain.

5. A control method for a power electronic secondary power supply as described in any one of claims 1 to 4, characterized in that, Includes the following steps: When information bit 1 needs to be transmitted, information bit 1 is extended to 0101. In the current cycle, chip 0 is transmitted first, and the LLC converter stops working. In the next cycle, chip 1 is transmitted, injecting a one-cycle high-frequency sine wave into the power grid. This process continues for the next two cycles of chip 0 and chip 1 transmission until information bit 1 transmission is completed. When information bit 0 needs to be transmitted, information bit 0 is extended to 0011. In two consecutive cycles, two chips 0 are transmitted sequentially. During these two cycles, the LLC converter does not work. In the next two consecutive cycles, two chips 1 are transmitted sequentially. The LLC converter works during these two consecutive cycles, injecting two cycles of high-frequency sine waves into the power grid.

6. The method according to claim 5, characterized in that, Also includes: The output voltage of the LLC converter is subtracted from the output voltage reference value to generate the output voltage error. The output voltage error is sent to the PI controller to generate the input current reference amplitude. The input voltage of the BOOST module is divided by the BOOST module input voltage amplitude to obtain the input current reference phase. The input current reference amplitude is multiplied by the input current reference phase to generate the input current reference instantaneous value. The input current reference instantaneous value is subtracted from the input current sampling value of the BOOST module, and the difference is sent to the PI controller to obtain the duty cycle of each MOSFET in the BOOST module.

7. A control system for a power electronic secondary power supply, comprising a memory, a processor, and a computer program stored in the memory; characterized in that, The processor executes the computer program to implement the steps of the method of claim 5 or 6.

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