Junction box power supply system for seabed observation network and control method

Abstract

The invention discloses a junction box power supply system for a submarine observation network and a control method, and belongs to the technical field of submarine observation equipment power supply. The system comprises a pre-stage ISOP isolation type DC / DC converter, a post-stage voltage stabilization DC / DC converter and a reverse energy feedback DC / DC converter. The front-stage ISOP isolated DC / DC converter adopts a multi-module input series and output parallel structure, and the input end is connected with a seabed direct current transmission cable system; the rear-stage voltage stabilization DC / DC converter provides stable electric energy for the observation instrument, and the reverse energy feedback DC / DC converter feeds excess energy back to the direct current transmission cable system. The submodule input voltage-sharing control is realized through a bidirectional voltage comparison algorithm, the bus voltage is adjusted by combining dual-mode power feedback control, the output voltage is stabilized by adopting a bus voltage feed-forward double-closed-loop control strategy, the wide input voltage and the high fault-tolerant capability are realized, and the reliability and the energy transmission efficiency of a submarine observation network power supply system can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply for seabed observation equipment, and in particular to a junction box power supply system and a control method for a seabed observation network. Background Art

[0002] In recent years, with the development of offshore new energy technologies and the implementation of the national energy security strategy, the seabed observation network not only undertakes the task of seabed observation, but also meets the needs of power transmission of offshore new energy power stations. Traditional seabed observation networks are limited by the voltage reduction ratio and power transmission efficiency of the junction box power supply. They usually use a lower cable voltage and can only meet the power needs of low-voltage, low-power, and small-range seabed observation instruments. When transmitting high-power offshore new energy power, it will cause a lot of power loss. Therefore, designing a high-input voltage, high-power, and high-efficiency junction box power supply is of great significance to improve the cable voltage of the seabed observation network for high-power offshore power transmission.

[0003] At present, the power supply of the junction box for the seabed observation network mostly adopts a two-stage junction box solution. The main junction box converts the voltage of the seabed observation network cable system into a DC low voltage, and the secondary junction box converts the DC low voltage into the working voltage of conventional underwater scientific instruments. However, the existing seabed observation network junction box design has the following disadvantages:

[0004] 1. Most main junction boxes use an input series output parallel (ISOP) structure to increase the input voltage of the junction box. However, there is a voltage balancing problem among the modules in the ISOP structure. In actual use, it may cause a surge in the voltage of a single sub-module, breaking down the power device of the sub-module and causing a short circuit.

[0005] 2. The main junction box often uses open-loop control. However, when the isolated DC / DC converter is unloaded or lightly loaded, the output voltage will soar, which may cause the input voltage of the secondary junction box to be too high and break down the secondary junction box.

[0006] 3. The two-stage junction box design uses low-voltage DC as the intermediate voltage. The introduction of low-voltage DC cables increases power transmission losses, which is not conducive to high-power power transmission of offshore renewable energy. The multi-module design increases equipment maintenance costs. Summary of the invention

[0007] The problem to be solved by the present invention is to provide a junction box power supply system for a submarine observation network, which has a wide input voltage and high fault tolerance, and can improve the reliability and energy transmission efficiency of the submarine observation network power supply system.

[0008] The present invention adopts the following technical solution: a junction box power supply system for a seabed observation network, the topology structure of which includes: a front-stage ISOP isolated DC / DC converter, a rear-stage voltage-stabilized DC / DC converter, and a reverse-feedback DC / DC converter.

[0009] The front-stage ISOP isolated DC / DC converter has an input end connected to the DC transmission cable system of the seabed observation network, and an output end that is a DC low-voltage bus; the front-stage ISOP isolated DC / DC converter includes a plurality of isolated DC / DC converter submodules with inputs connected in series and outputs connected in parallel;

[0010] The post-stage voltage-stabilizing DC / DC converter has an input end connected to the output end of the ISOP isolated DC / DC converter, and an output end connected to the power supply port of the seabed observation instrument;

[0011] The reverse energy feeding DC / DC converter has an input end connected to the output end of the ISOP isolated DC / DC converter, and an output end connected back to the DC transmission cable system.

[0012] The technical solution of the present invention also includes a control method for a junction box power supply system for a seabed observation network, which is applied to the above-mentioned junction box power supply system and includes the following steps:

[0013] S1. Using voltage balancing control on each DC / DC converter submodule in the previous ISOP isolated DC / DC converter, obtaining the maximum input voltage of each DC / DC converter submodule through a bidirectional voltage comparison method, and determining the working state of each DC / DC converter submodule;

[0014] S2. Perform output voltage regulation control on the post-stage voltage-stabilized DC / DC converter, and adopt bus voltage feedforward dual closed-loop control strategy to perform voltage-current dual closed-loop control; generate an inductor current reference value through the voltage outer loop to obtain an inductor current error; generate an output signal through the current inner loop from the inductor current error; perform feedforward correction on the output signal through the feedforward compensation path, and output the feedforward corrected signal to the PWM / PFM modulator to stabilize the output voltage;

[0015] S3. The reverse-feedback DC / DC converter is controlled based on the DC low-voltage bus voltage, and a dual-mode control method of a power closed-loop control mode and a voltage-power dual closed-loop control mode is adopted. The control mode is switched through a hysteresis comparison strategy to feed back excess energy to the DC transmission cable to adjust the DC low-voltage bus voltage.

[0016] Preferably, in the front-stage ISOP isolated DC / DC converter, each DC / DC converter submodule adopts a ring communication topology, each submodule establishes a communication link only with two adjacent submodules, and obtains the maximum input voltage of each DC / DC converter submodule through bidirectional comparison, specifically including:

[0017] Downlink comparison stage: The first-level submodule passes the input voltage of this module as the maximum downlink value to the secondary, and the subsequent submodules compare the downlink received value V RXDAfter the input voltage value of this module, the larger value is passed downward;

[0018] Uplink comparison stage: The final submodule passes the input voltage of this module to the front stage as the maximum value of the uplink, and the front submodule compares the uplink receiving value V RXU After the input voltage value of this module, the larger value is transmitted upward;

[0019] Maximum value determination stage: Each submodule compares the received uplink and downlink maximum values ​​and takes the larger value as the maximum input voltage of each DC / DC converter submodule.

[0020] Furthermore, the voltage balancing control method of each DC / DC converter submodule specifically includes:

[0021] Threshold voltage generation: Multiply the maximum input voltage by the corresponding proportionality factor k 1 (0 <k 1 <1) Obtaining the normal working voltage threshold of the submodule;

[0022] Working state selection: If the submodule input voltage is greater than or equal to the normal working voltage threshold of the submodule, the submodule works normally; if the submodule input voltage is less than the normal working voltage threshold of the submodule, the duty cycle is reduced by ΔD. If the submodule input voltage is still lower than the threshold voltage after the duty cycle is reduced, the submodule is turned off.

[0023] Preferably, the post-stage voltage-stabilizing DC / DC converter adopts a bus voltage feedforward double closed-loop control strategy, specifically including:

[0024] Sampling unit: DC bus voltage V bus , the inductor current I of the post-stage voltage-stabilized DC / DC converter L And the output voltage V o Sampling is performed using a reference voltage V ref Subtract the output voltage V o Get the output voltage error;

[0025] Voltage-current double closed loop: The voltage outer loop generates the inductor current reference value I through the first PI controller using the output voltage error ref , using the inductor current reference value I ref Subtract the inductor current sampling value I L The inductor current error is obtained, and the current inner loop generates a d' signal through the second PI controller using the inductor current error;

[0026] Feedforward compensation path: through the DC bus voltage sampling value V bus , perform feedforward correction operation d = K·d' / V on the output signal of the second PI controller bus , where K is the feedforward gain coefficient, which is ultimately output to the PWM / PFM modulator.

[0027] Preferably, the reverse-feedback DC / DC converter adopts a dual-mode control method, and the specific steps include:

[0028] S5.1, reference voltage setting, determining the ideal DC low-voltage bus voltage value V according to the load characteristics of the preceding ISOP isolated DC / DC converter bus_ref ;

[0029] S5.2, threshold voltage calculation, the ideal DC bus voltage value V bus_ref Multiply by the corresponding proportionality factor k 2 , k 3 (1 <k 2 <k 3 <2) respectively obtain the power feedback voltage threshold V bus_th And the dual-loop control voltage threshold V bus_max ;

[0030] S5.3, during the DC low voltage bus voltage rising process, if V bus_th <V bus <V bus_max , the reverse feed DC / DC converter starts the power closed loop control mode. If V bus ≥V bus_max , the reverse feeding DC / DC converter switches to the voltage-power dual closed-loop control mode.

[0031] Furthermore, the reverse feedback DC / DC converter control mode is switched through a hysteresis comparison strategy. During the DC low voltage bus voltage drop, when the DC low voltage bus voltage drops from higher than V bus_max Drop to (V bus_th , V bus_max ), maintain the voltage-power dual closed-loop control mode; when the DC low-voltage bus voltage continues to drop to V bus_th When the reverse feeding DC / DC converter is turned off.

[0032] Furthermore, the power closed-loop control circuit of the reverse-feedback DC / DC converter comprises:

[0033] Power sampling unit: It is composed of DC bus voltage sampling, reverse feeding DC / DC converter input current sampling, multiplier and low pass filter. The reverse feeding DC / DC converter input current sampling value I infb The signal is connected to the input end of the low-pass filter, and the output end of the low-pass filter is connected to the first input end of the multiplier. The DC bus voltage sampling value V bus Connecting the second input terminal of the multiplier, the output terminal of the multiplier is used as the output terminal of the power sampling unit, that is, the power sampling value;

[0034] The error adjustment unit is composed of a first subtractor and a third PI controller, wherein the input power reference value is connected to the positive input terminal of the first subtractor, the output terminal of the power sampling unit is connected to the negative input terminal of the first subtractor, and the output terminal of the first subtractor is connected to the input terminal of the third PI controller;

[0035] PWM / PFM modulation unit: the output end of the third PI controller is connected to the input end of the PWM / PFM modulator, and the output end of the PWM / PFM modulator is connected to the control end of the reverse feeding DC / DC converter.

[0036] Furthermore, the reverse feeding DC / DC converter voltage-power dual closed-loop control mode loop superimposes a voltage outer loop on the basis of the power closed-loop control:

[0037] The voltage outer loop is composed of the second subtractor and the fourth PI controller, which converts the ideal DC bus voltage value V bus_ref The voltage reference value is connected to the negative input terminal of the second subtractor, the DC bus voltage sampling value is connected to the positive input terminal of the second subtractor, the output terminal of the second subtractor is connected to the input terminal of the fourth PI controller, and the output of the fourth PI controller is used as a power reference value to provide a power reference benchmark for the inner loop, forming a cascade control structure.

[0038] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0039] 1. The junction box power supply system of the present invention is connected to the submarine DC transmission cable system through the front-stage ISOP isolated DC / DC converter, provides stable power for the observation instrument through the rear-stage voltage-stabilized DC / DC converter, and feeds back the excess energy to the DC transmission cable system through the reverse-feedback DC / DC converter. It has a wide input voltage and high fault tolerance, and can improve the reliability and energy transmission efficiency of the submarine observation network power supply system.

[0040] 2. The junction box power supply system of the present invention realizes sub-module input voltage equalization control through a bidirectional voltage comparison algorithm, adjusts the bus voltage in combination with dual-mode power feedback control, and adopts a bus voltage feedforward double closed-loop control strategy to stabilize the output voltage, thus solving the problems of low energy utilization and bus voltage instability in traditional submarine power supply systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the power supply system of the junction box used in the seabed observation network of the present invention

[0042] Figure 2 This is a topology diagram of a power supply system of a junction box used in a submarine observation network according to an embodiment of the present invention;

[0043] Figure 3A schematic diagram of the communication strategy and bidirectional voltage comparison flow of the DC / DC converter submodule of the present invention;

[0044] Figure 4 This is a bus voltage feedforward double closed-loop control block diagram of the back-stage voltage-stabilizing DC / DC converter of the present invention;

[0045] Figure 5 It is a dual-mode control block diagram of the reverse energy feeding DC / DC converter of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the application is further elaborated in detail below in conjunction with the accompanying drawings. The described embodiments are only a part of the embodiments involved in the present invention. All non-innovative embodiments of other researchers in the field on this embodiment belong to the protection scope of the present invention. At the same time, for the step numbering in the embodiment of the present invention, it is only set for the convenience of explanation, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0047] In one embodiment of the present invention, a power supply architecture and control method with 3kV high-voltage DC input and 48V low-voltage output is proposed for the power supply system of the seabed observation network junction box. Figure 1 As shown, it includes: a front-stage ISOP isolated DC / DC converter, a rear-stage voltage-stabilized DC / DC converter, and a reverse-feedback DC / DC converter.

[0048] Specifically, the input end of the front-stage ISOP isolated DC / DC converter is connected to the DC transmission cable system of the seabed observation network, and the output end is the DC low-voltage bus; the input end of the rear-stage voltage-stabilizing DC / DC converter is connected to the output end of the ISOP isolated DC / DC converter, and the output end is connected to the power supply port of the seabed observation instrument; the input end of the reverse-feedback LLC converter is connected to the output end of the ISOP isolated DC / DC converter, and the output end is connected back to the DC transmission cable system.

[0049] The topology of the junction box power supply system provided in this embodiment is as follows: Figure 2As shown in the figure, the front-stage ISOP isolated DC / DC converter adopts ISOP-LLC converter, which is composed of 5 LLC converter sub-modules with serial input and parallel output. Without considering the difference in device parameters, the input voltage of each sub-module is 600V, which can effectively reduce the voltage stress of the switch tube and increase the input voltage of the junction box power system. The back-stage voltage-stabilized DC / DC converter adopts Buck converter, which adopts wide input voltage design and realizes output voltage stability through feedforward compensation double closed-loop control. In view of the light-load output voltage surge characteristic of LLC converter, in order to adjust the DC bus voltage, a reverse energy DC / DC converter is added to feed back excess energy to the DC transmission cable system. The reverse energy DC / DC converter adopts LLC converter.

[0050] In practical applications, due to the discreteness of device parameters and the independence of driving signals of various LLC sub-modules, it is easy to cause uneven input voltages of various LLC sub-modules, resulting in a surge in voltage of a single sub-module, breaking down the sub-module power device and causing a short circuit.

[0051] In order to solve the problem of uneven input voltage of LLC submodules, the present invention realizes voltage equalization input of LLC submodules by combining a bidirectional voltage comparison algorithm with a voltage equalization control method.

[0052] Specifically, this embodiment obtains the maximum input voltage V of each LLC submodule through a ring communication topology and a bidirectional voltage comparison algorithm. in_max .like Figure 3 As shown in the figure, each LLC converter submodule adopts a ring communication topology, and each submodule only establishes a communication link with two adjacent submodules. In the downlink comparison stage, the first-level submodule transmits the input voltage of this module as the downlink maximum value to the secondary, and the subsequent submodules compare the uplink received value V RXD The larger value is passed downward after comparing with the input voltage value of this module; in the uplink comparison stage, the final submodule passes the input voltage of this module as the uplink maximum value to the front stage, and the front stage submodule compares the uplink receiving value V RXU The larger value is transmitted upward after comparing with the input voltage value of this module; in the maximum value determination stage, each submodule compares the received maximum values ​​of the uplink and downlink, and takes the larger value as the maximum input voltage of each LLC converter submodule.

[0053] After obtaining the maximum input voltage of each LLC submodule, multiply the maximum input voltage by the corresponding proportional coefficient k 1 Get the normal working voltage threshold V of the submodule th . Where k 1 Should be slightly less than 1 to ensure that all submodules can work normally; if k 1 Equal to 1, in actual circuit control it may cause each module to be in the off state.

[0054] In this embodiment, k1 Taking 0.96, we have:

[0055] V th =k 1 ·V in_max

[0056] If the input voltage of the nth submodule is greater than or equal to the normal working voltage threshold of the submodule, that is, V inn ≥V th (n=1, 2, ... 5), the nth submodule works normally; if the input voltage of the nth submodule is less than the normal working voltage threshold of the submodule, that is, V inn <V th (n=1, 2, ... 5), the duty cycle of the nth submodule is reduced by ΔD (ΔD is 5% in this embodiment). If the input voltage of the nth submodule is still lower than the threshold voltage after the duty cycle is reduced, the submodule is turned off.

[0057] In order to stabilize the output voltage of the junction box power supply and meet the power supply requirements of various seabed observation instruments, the post-stage voltage-stabilized DC / DC converter adopts the bus voltage feed-forward voltage outer loop and current inner loop control strategy.

[0058] In this embodiment, Figure 4 As shown, set the reference voltage V ref The output voltage is 48V, and V o . With reference voltage V ref Subtract the output voltage V o The output voltage error is obtained, and the output voltage error generates the inductor current reference value I through the first PI controller ref . Using the inductor current reference value I ref Subtract the inductor current sampling value I L The inductor current error is obtained, and the current inner loop generates a d' signal through the second PI controller using the inductor current error;

[0059] In order to reduce the influence of the DC low-voltage bus voltage fluctuation on the output voltage of the subsequent voltage-stabilized DC / DC converter, the present invention uses the DC low-voltage bus voltage to perform feedforward compensation on the control loop of the subsequent voltage-stabilized DC / DC converter.

[0060] Specifically, the feedforward gain coefficient K is introduced. For the Buck converter in this embodiment, K is set to 1: bus , perform feedforward correction operation d = K·d' / V on the output signal of the second PI controller bus , and finally output to the PWM modulator.

[0061] Since the front-stage ISOP-LLC converter adopts an open-loop design, in order to maintain the stability of the DC low-voltage bus voltage, the switching frequency of each LLC submodule is slightly lower than the resonant frequency of the resonant cavity, and the LLC converter operates in the DC transformer (DCX) mode. However, although the selection of the LLC working mode can maintain the stability of the DC low-voltage bus voltage to a certain extent, in the actual circuit, the LLC converter will still experience a surge in output voltage under no-load and light-load conditions, resulting in the breakdown of the power devices in the subsequent circuit.

[0062] In order to solve this problem, the present invention feeds power back to the DC transmission cable system through a reverse-feedback LLC converter to suppress the DC low-voltage bus voltage surge.

[0063] Specifically, in this embodiment, the front-stage ISOP-LLC converter is designed with a rated input of 3kV and a rated output of 500V. Due to the fluctuation of the input voltage and load of the DC transmission cable, the output voltage V bus It will fluctuate between 500V and 800V.

[0064] Since the voltage fluctuation range of the DC low-voltage bus is large, a dual-mode energy feedback control algorithm is designed. When the bus voltage rises to a low level, power closed-loop control is used to return power. When the bus voltage rises to a high level, voltage-power dual closed-loop control is used to suppress the DC low-voltage bus voltage surge.

[0065] The dual-mode energy feedback control algorithm of the reverse-feedback LLC converter specifically includes:

[0066] Reference voltage setting: Since the rated input of the previous ISOP-LLC converter is 3kV and the rated output is 500V, the expected DC low-voltage bus voltage V bus_ref 500V;

[0067] Threshold voltage calculation: The ideal DC bus voltage value V bus_ref Multiply by the corresponding proportionality factor k 2 , k 3 (1 <k 2 <k 3 <2) respectively obtain the power feedback voltage threshold V bus_th And the dual-loop control voltage threshold V bus_max .

[0068] In this embodiment, the voltage fluctuates from 500V to 800V, so k 2 Take 1.2, k 3 Taking 1.4, we have:

[0069] V bus_th =k 2 ·V bus_ref =600V

[0070] V bus_max =k 3 ·V bus_ref =700V

[0071] During the DC low voltage bus voltage rising process, if V bus_th <V bus <V bus_max , the reverse feed DC / DC converter starts the power closed loop control mode. If V bus ≥V bus_max , the reverse feeding DC / DC converter switches to the voltage-power dual closed-loop control mode.

[0072] Since the power closed-loop control mode has limited ability to suppress the DC bus voltage, when the DC low-voltage bus voltage drops, if the reverse-feedback LLC converter switches from the voltage-power dual closed-loop control mode to the power closed-loop control mode, the DC low-voltage bus may drop below the dual-loop control voltage threshold V bus_max Therefore, the two control modes of the reverse-feedback LLC converter adopt a hysteresis comparison switching scheme.

[0073] During the DC low-voltage bus voltage drop, when the DC low-voltage bus voltage drops from higher than V bus_max Drop to (V bus_th , V bus_max ), the dual-loop control mode is maintained; when the DC low-voltage bus voltage continues to drop to V bus_th When the reverse feeding DC / DC converter is turned off.

[0074] Different from the PFM voltage-current dual-loop control mode of the conventional LLC converter, the reverse-feedback LLC converter described in this embodiment adopts a power closed-loop control, such as Figure 5 As shown, Figure 5 (a) shows the process of power closed-loop control of the reverse-feedback DC / DC converter. Figure 5 (b) in FIG. 5 shows the process of voltage-power closed-loop control of the backfeed DC / DC converter.

[0075] Specifically, in this embodiment, the power closed-loop control of the backfeed LLC converter includes a power sampling unit, an error adjustment unit, and a PWM modulation unit.

[0076] The power sampling unit is used to obtain the power sampling value of the backfeed LLC converter. infbThe input current of the LLC converter is not a DC current, so the input current of the reverse-feedback LLC converter needs to be processed by low-pass filtering. The cutoff frequency of the low-pass filter should be much lower than the switching frequency, usually 1 / 1000 to 1 / 2000 of the switching frequency.

[0077] The switching frequency of the backfeed LLC converter in this embodiment is 500kHz, the cutoff frequency of the low-pass filter is selected to be 318.5Hz, and the transfer function of the low-pass filter is shown in the following formula:

[0078]

[0079] In the formula, τ is 100, I infb The DC component of the LLC converter input current is obtained by low-pass filtering and multiplied by the bus voltage sampling value V bus Get the power sampling value P of the reverse feeding LLC converter in .

[0080] The error adjustment unit is composed of a first subtractor and a third PI controller. The input power reference value in the power closed-loop control is determined according to the rated power of the preceding ISOP-LLC converter. Through the analysis of the load characteristics of the actual circuit of the ISOP-LLC converter, it can be known that the input power reference value of the reverse-feedback LLC converter is selected as about 1 / 6 of the rated power of the ISOP-LLC converter. The power reference value in this embodiment is selected as 500W. The power reference value is connected to the positive input end of the first subtractor, the output end of the power sampling unit is connected to the negative input end of the first subtractor, and the output of the first subtractor is the input power error. The output end of the first subtractor is connected to the input end of the third PI controller.

[0081] In order to prevent the duty cycle of the reverse-feedback LLC converter from exceeding 0.5, the third PI controller adopts a PI controller with anti-integral saturation, and its transfer function is as follows:

[0082]

[0083] Among them, K p1 Represents proportional gain, K i1 represents the integral gain, and s represents the Laplace transform variable.

[0084] According to the specific parameters of the backfeed LLC converter in this embodiment, the specific parameters of the third PI controller are selected as: K p1 =0.5, K i1 =50.

[0085] Modulation unit, the reverse-feedback LLC converter in this embodiment adopts a PWM modulation mode, the output end of the third PI controller is connected to the input end of the PWM modulator, and the modulation signal output by the PWM modulator is connected to the control end of the reverse-feedback LLC converter.

[0086] To further suppress the DC low-voltage bus voltage surge, when V bus ≥V bus_max When the reverse energy LLC converter adopts voltage-power dual closed-loop control, it is composed of voltage outer loop and power inner loop control. The voltage outer loop is composed of the second subtractor and the fourth PI controller. Since the higher the DC bus voltage is, the higher the energy that needs to be sent back to the DC transmission cable system by the reverse energy LLC is. Therefore, the ideal DC bus voltage value V bus_ref The voltage reference value is connected to the negative input terminal of the second subtractor, and the DC bus voltage sampling value is connected to the positive input terminal of the second subtractor to obtain the bus voltage error value.

[0087] The output end of the second subtractor is connected to the input end of the fourth PI controller. The output of the fourth PI controller is used as a power reference value to provide a power reference benchmark for the inner loop to form a cascade control structure. The specific parameters of the fourth PI controller are selected as follows: K p2 =5, K i2 =300.

[0088] In summary, the present invention is suitable for the junction box power supply system of the seabed observation network. The front-stage ISOP isolated DC / DC converter adopts a multi-module input series output parallel structure, and the input end is connected to the seabed DC transmission cable system; the rear-stage voltage-stabilizing DC / DC converter provides stable power for the observation instrument, and the reverse-feedback DC / DC converter feeds back excess energy to the DC transmission cable system. At the same time, the sub-module input voltage equalization control is realized through a bidirectional voltage comparison algorithm, and the bus voltage is adjusted in combination with the dual-mode power feedback control. The bus voltage feedforward dual closed-loop control strategy is used to stabilize the output voltage, which solves the problems of low energy utilization and bus voltage instability in traditional seabed power supply systems. It has a wide input voltage and high fault tolerance, and can improve the reliability and energy transmission efficiency of the seabed observation network power supply system.

[0089] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0090] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A junction box power supply system for a submarine observation network, characterized in that: The topology of the connection box power supply system includes: a front-stage ISOP isolated DC / DC converter, a rear-stage regulated DC / DC converter, and a reverse energy feedback DC / DC converter; For the front-stage ISOP isolated DC / DC converter, its input terminal is connected to the DC transmission cable system of the submarine observation network, and its output terminal is the DC low-voltage bus, which includes multiple isolated DC / DC converter sub-modules with series inputs and parallel outputs; For the rear-stage regulated DC / DC converter, its input terminal is connected to the output terminal of the ISOP isolated DC / DC converter, and its output terminal is connected to the power supply port of the submarine observation instrument to provide stable electrical energy; For the reverse energy feedback DC / DC converter, its input terminal is connected to the output terminal of the ISOP isolated DC / DC converter, and its output terminal is connected back to the DC transmission cable system of the submarine observation network.

2. The junction box power supply system for the submarine observation network according to claim 1 is characterized in that: In the front-stage ISOP isolated DC / DC converter, each DC / DC converter sub-module adopts a ring communication topology. Each sub-module only establishes a communication link with the adjacent two sub-modules, and obtains the maximum input voltage of each DC / DC converter sub-module through bidirectional voltage comparison, specifically including: Downlink comparison stage: The first-stage DC / DC converter submodule transmits the input voltage as the downlink maximum value to the secondary DC / DC converter submodule, and the subsequent DC / DC converter submodules compare the downlink received value V RXD After comparing with the current submodule input voltage value, the larger value is passed downward; Uplink comparison stage: The final DC / DC converter submodule passes the input voltage as the uplink maximum value to the forward DC / DC converter submodule, and the forward DC / DC converter submodule compares the uplink received value V RXU After comparing with the current submodule input voltage value, the larger value is passed upward; Maximum value determination stage: Each DC / DC converter sub-module compares the received maximum values of the upstream and downstream, and takes the larger value of the received values of the upstream and downstream as the maximum input voltage of each DC / DC converter sub-module.

3. The junction box power supply system for the seabed observation network according to claim 2 is characterized in that: The DC / DC converter sub-module adopts an equal voltage control method, specifically including: Threshold voltage generation: Multiply the maximum input voltage by a corresponding proportionality coefficient k1, where 0 < k1 < 1, to obtain the normal operating voltage threshold of the DC / DC converter sub-module; Operating state selection: If the input voltage of the DC / DC converter sub-module is greater than or equal to the normal operating voltage threshold of the sub-module, the DC / DC converter sub-module operates normally; if the input voltage of the DC / DC converter sub-module is less than the normal operating voltage threshold of the sub-module, the duty cycle is reduced by ΔD. If the input voltage of the sub-module is still lower than the threshold voltage after the duty cycle is reduced, the current DC / DC converter sub-module is turned off.

4. The junction box power supply system for the submarine observation network according to claim 1 is characterized in that: The rear-stage regulated DC / DC converter adopts a bus voltage feed-forward double closed-loop control strategy, specifically including: Sampling unit: DC low voltage bus voltage V bus , the inductor current I of the post-stage voltage-stabilized DC / DC converter L And the output voltage V o Sampling is performed using a reference voltage V ref Subtract the output voltage V o Get the output voltage error; Voltage-current double closed loop: The voltage outer loop generates the inductor current reference value I through the first PI controller using the output voltage error ref , using the inductor current reference value I ref Subtract the inductor current sampling value I L The inductor current error is obtained, and the current inner loop generates a d' signal output through the second PI controller based on the inductor current error; Feedforward compensation path: through the DC low-voltage bus voltage sampling value V bus , perform feedforward correction operation on the output signal of the second PI controller: d=K·d’ / V bus Where K is the feed-forward gain coefficient; the signal d after feed-forward correction is output to the PWM / PFM modulator.

5. The junction box power supply system for the seabed observation network according to claim 1, characterized in that: The reverse energy feedback DC / DC converter adopts a dual-mode control method, and the specific steps include: Reference voltage setting: Determine the ideal DC low-voltage bus voltage value V according to the load characteristics of the preceding ISOP isolated DC / DC converter. bus_ref ; Threshold voltage calculation: Multiply the ideal DC bus voltage value V bus_ref by the corresponding proportionality coefficients k2 and k3, where 1 < k2 < k3 < 2, to obtain the power feedback voltage threshold V bus_th and the double-loop control voltage threshold V bus_max ; Control mode switching: During the DC low voltage bus voltage rise process, if V bus_th <V bus <V bus_max , the reverse feed DC / DC converter starts the power closed loop control mode; if V bus ≥V bus_max , the reverse feeding DC / DC converter switches to the voltage-power dual closed-loop control mode.

6. The junction box power supply system for the seabed observation network according to claim 5, characterized in that: For the reverse energy feedback DC / DC converter, the control mode is switched through a hysteresis comparison strategy, specifically including: During the DC low-voltage bus voltage drop, when the DC low-voltage bus voltage drops from higher than V bus_max Drop to (V bus_th , V bus_max ), maintain the voltage-power dual closed-loop control mode; when the DC low-voltage bus voltage continues to drop to V bus_th When the reverse feeding DC / DC converter is turned off.

7. The junction box power supply system for the seabed observation network according to claim 5, characterized in that: For the reverse energy feedback DC / DC converter, the power closed-loop control mode loop includes: Power sampling unit: It is composed of DC bus voltage sampling, reverse feeding DC / DC converter input current sampling, multiplier and low pass filter; the reverse feeding DC / DC converter input current sampling value I infb The signal is connected to the input of the low-pass filter, and the output of the low-pass filter is connected to the first input of the multiplier. The DC bus voltage sampling value V bus Connecting the second input terminal of the multiplier, the output terminal of the multiplier is used as the output terminal of the power sampling unit to obtain the power sampling value of the reverse feeding DC / DC converter; Error adjustment unit: It consists of a first subtractor and a third PI controller. The input power reference value is connected to the positive input terminal of the first subtractor, the output terminal of the power sampling unit is connected to the negative input terminal of the first subtractor, and the output terminal of the first subtractor is connected to the input terminal of the third PI controller; PWM / PFM modulation unit, the output terminal of the third PI controller is connected to the input terminal of the PWM / PFM modulator, and the output terminal of the PWM / PFM modulator is connected to the control terminal of the reverse energy feedback DC / DC converter.

8. A junction box power supply system and control method suitable for a submarine observation network according to claim 7, characterized in that: The reverse feed DC / DC converter voltage-power dual closed-loop control mode loop superimposes a voltage outer loop on the basis of the power closed-loop control mode: The voltage outer loop is composed of a second subtractor and a fourth PI controller, which converts the ideal DC bus voltage value V bus_ref The voltage reference value is connected to the negative input terminal of the second subtractor, the DC bus voltage sampling value is connected to the positive input terminal of the second subtractor, the output terminal of the second subtractor is connected to the input terminal of the fourth PI controller, and the output of the fourth PI controller is used as a power reference value to provide a power reference benchmark for the inner loop, forming a cascade control structure.

9. A control method for a junction box power supply system for a seafloor observation network, applied to the junction box power supply system according to any one of claims 1 to 8, characterized in that: The steps include: S1. Using voltage balancing control on each DC / DC converter submodule in the previous ISOP isolated DC / DC converter, obtaining the maximum input voltage of each DC / DC converter submodule through a bidirectional voltage comparison method, and determining the working state of each DC / DC converter submodule; S2. Perform output voltage regulation control on the post-stage voltage-stabilized DC / DC converter, and adopt bus voltage feedforward dual closed-loop control strategy to perform voltage-current dual closed-loop control; generate an inductor current reference value through the voltage outer loop to obtain an inductor current error; generate an output signal through the current inner loop from the inductor current error; perform feedforward correction on the output signal through the feedforward compensation path, and output the feedforward corrected signal to the PWM / PFM modulator to stabilize the output voltage; S3. The reverse-feedback DC / DC converter is controlled based on the DC low-voltage bus voltage, and a dual-mode control method of a power closed-loop control mode and a voltage-power dual closed-loop control mode is adopted. The control mode is switched through a hysteresis comparison strategy to feed back excess energy to the DC transmission cable to adjust the DC low-voltage bus voltage.

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