Soft start current-limiting control method and system for hybrid ISOP direct-current transformer

Abstract

The invention provides a soft start current-limiting control method and system for a hybrid ISOP direct-current transformer, and relates to the technical field of power conversion control, and the method comprises the steps: calculating the leakage inductance peak current of a dual-active bridge converter and the average current of the secondary side of the transformer according to the working state data of the dual-active bridge converter in an input-series output-parallel ISOP topological structure; constructing an extended state observer by using the Kirchhoff's law and the relationship between the capacitor voltage and the current, and estimating the average current of the secondary side of the transformer of the series resonant converter; obtaining a resonant cavity peak current of the series resonant converter under the current duty ratio; under the condition of ensuring that the leakage inductance current of the dual-active bridge converter is smaller than a set current limit value, the capacitor voltage at the input side of the series resonant converter is controlled to be close to a reference value by adjusting the internal shift phase ratio or the single shift phase ratio of the DAB; and adjusting the duty ratio of the series resonant converter until the output voltage of the hybrid ISOP direct-current transformer reaches a set value, and ending the starting process.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power conversion control, and in particular to a soft-start current limiting control method and system for a hybrid ISOP DC transformer. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] As the core equipment in the energy internet, the power router plays an important role in utilizing renewable energy, managing energy flow, and improving the stability of the power grid. Due to the large number of voltage / power levels of various DC "source-load-storage", the power router with a dual DC bus structure has more advantages in terms of cost, efficiency, and number of conversion poles. Among them, the bidirectional isolation DC transformer connected to the dual DC bus has become the core equipment of the power router.

[0004] Among various DC transformers, the extremely efficient Series Resonant Converter (SRC) and the easily power-controlled Dual-Active Bridge (DAB) converter are the two most commonly used topologies. They are usually combined in the Input-Series-Output-Parallel (ISOP) topology, which combines the advantages of both, with high flexibility, high efficiency, high reliability, and broad application prospects.

[0005] However, the hybrid ISOP DC transformer has the disadvantages of the two topologies of DAB and SRC, as well as the coupling effect between them, which leads to problems such as overcurrent, resonant capacitor overvoltage, switch device shutdown overvoltage, input capacitor voltage imbalance, etc. during the startup process, which may even cause device damage in severe cases. Currently, there is little research on the soft start strategy of the hybrid ISOP DC transformer.

[0006] Currently, there is a three-stage DC transformer startup accurate current limiting method that can accurately limit the peak current of the DAB and SRC submodules and balance the input side capacitor voltage between the submodules. However, this method requires adding additional detection circuits and voltage sensors to the resonant cavity of the SRC submodule, which will increase the system's additional hardware cost and is also difficult to implement. Summary of the invention

[0007] In order to solve the above problems, the present disclosure proposes a hybrid ISOP DC transformer soft-start current limiting control method and system, which does not require a resonant cavity voltage or current sensor, limits the surge current of the hybrid ISOP DC transformer during startup, balances the input capacitor voltage, shortens the response time, makes the output voltage reach the set value smoothly and reduces overshoot, thereby reducing costs and implementation difficulty.

[0008] According to some embodiments, the present disclosure adopts the following technical solutions:

[0009] A hybrid ISOP DC transformer soft-start current limiting control method includes:

[0010] In the input series output parallel ISOP topology, obtain the operating status data of the dual active bridge converter and the series resonant converter, as well as the output voltage and output current of the ISOP DC transformer;

[0011] According to the working state data of the dual active bridge converter, the peak value of the leakage inductance current of the dual active bridge converter and the average current of the secondary side of the transformer under the current phase shift parameters are calculated; Kirchhoff's law and the relationship between capacitor voltage and current are used to analyze the relationship between the total output current of the hybrid ISOP DC transformer and the output current of the dual active bridge converter and the output current of the series resonant converter; an extended state observer is constructed to estimate the average current of the secondary side of the transformer of the series resonant converter;

[0012] The peak voltage of the resonant capacitor in one switching cycle is estimated according to the average current value of the secondary side of the transformer of the series resonant converter, the capacitance value of the resonant capacitor, the transformer ratio, and the switching frequency; the resonant cavity peak current of the series resonant converter at the current duty cycle is obtained according to the input voltage, output voltage, transformer ratio, resonant inductance and resonant capacitor parameters of the series resonant converter, and the estimated resonant capacitor voltage peak value;

[0013] Under the condition that the peak current of the leakage inductance of the dual active bridge converter is ensured to be less than the set current limit value, the internal shift phase ratio or the single shift phase ratio of the dual active bridge converter is adjusted by the PI controller to control and adjust the input side capacitor voltage of the hybrid ISOP DC transformer to be close to the reference value. At the same time, the duty cycle of the series resonant converter is adjusted. When the duty cycle of the series resonant converter increases to the set value, the output voltage of the hybrid ISOP DC transformer reaches the set value, and the startup process ends.

[0014] According to some embodiments, the present disclosure adopts the following technical solutions:

[0015] Hybrid ISOP DC transformer soft start current limiting control system, including:

[0016] A data acquisition module is used to acquire the working state data of the dual active bridge converter and the series resonant converter, as well as the output voltage and output current of the ISOP DC transformer in the input series output parallel ISOP topology structure;

[0017] The calculation module is used to calculate the peak current of the leakage inductance of the dual active bridge converter and the average current of the secondary side of the transformer under the current phase shift parameters according to the working state data of the dual active bridge converter; obtain the relationship between the total output current of the hybrid ISOP DC transformer and the output current of the dual active bridge converter and the output current of the series resonant converter by using Kirchhoff's law and the relationship between capacitor voltage and current; construct an extended state observer to estimate the average current of the secondary side of the transformer of the series resonant converter; calculate the peak voltage of the resonant capacitor in one switching cycle according to the average current value of the secondary side of the transformer of the series resonant converter, the capacitance value of the resonant capacitor, the transformer ratio, and the switching frequency; obtain the resonant cavity peak current of the series resonant converter under the current duty cycle according to the input voltage, output voltage, transformer ratio, resonant inductance and resonant capacitor parameters of the SRC, and the estimated resonant capacitor voltage peak value;

[0018] The control current limiting module is used to adjust the internal shift phase ratio or the single shift phase ratio of the dual active bridge converter through the PI controller while ensuring that the peak current of the leakage inductance of the dual active bridge converter is less than the set current limit value, so as to control and adjust the input side capacitor voltage of the hybrid ISOP DC transformer to be close to the reference value, and at the same time, adjust the duty cycle of the series resonant converter. When the duty cycle of the series resonant converter increases to the set value, the output voltage of the hybrid ISOP DC transformer reaches the set value, and the startup process ends.

[0019] According to some embodiments, the present disclosure adopts the following technical solutions:

[0020] A computer program product comprises a computer program, wherein when the computer program is executed by a processor, the hybrid ISOP DC transformer soft-start current limiting control method is implemented.

[0021] According to some embodiments, the present disclosure adopts the following technical solutions:

[0022] A non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the hybrid ISOP DC transformer soft-start current limiting control method is implemented.

[0023] According to some embodiments, the present disclosure adopts the following technical solutions:

[0024] An electronic device comprises: a processor, a memory and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device executes the hybrid ISOP DC transformer soft-start current limiting control method.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The hybrid ISOP DC transformer soft-start current limiting control method disclosed in the present invention only needs to measure the input and output capacitor voltages and the load current, and uses an extended state observer to calculate the peak value of the leakage inductance current of the series resonant converter under the current duty cycle according to the circuit parameters. The circuit peak current can be monitored without adding redundant voltage or current sensors and detection circuits, which can reduce the system hardware cost. At the same time, the introduction of the extended state observer avoids the high-frequency noise problem caused by directly derivation of the output voltage.

[0027] The hybrid ISOP DC transformer soft start current limiting control method disclosed in the present invention has a simple calculation process. Under the condition that the peak value of the DAB leakage inductance current is less than the set current limit value, the internal shift phase D of the DAB is adjusted by the PI controller. IPS Or single shift comparison D SPS , so that the input capacitor voltage of the hybrid ISOP DC transformer is close to the reference value. At the same time, while ensuring that the current resonant cavity peak current is less than the set current limit value, slowly increase the duty cycle D of SRC. SRC When the duty cycle of SRC increases to 0.5, the output voltage of the hybrid ISOP DC transformer reaches near the set value, and the startup process ends. This process has low requirements on the performance of the controller. The present disclosure can accurately limit the peak current to avoid device damage due to overcurrent, while ensuring the converter transmission power and fast startup speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure.

[0029] Figure 1 The topology of the hybrid ISOP DC transformer of the embodiment of the present disclosure;

[0030] Figure 2 is an implementation block diagram of an embodiment of the present disclosure;

[0031] Figure 3 A control block diagram of a soft start strategy according to an embodiment of the present disclosure;

[0032] Figure 4 is a peak voltage estimation diagram of the SRC resonant capacitor according to an embodiment of the present disclosure;

[0033] Figure 5 is a schematic diagram of current flowing through node E according to an embodiment of the present disclosure;

[0034] Figure 6 is a state trajectory diagram of the SRC resonant cavity when starting up an embodiment of the present disclosure;

[0035] Figure 7 1 is a voltage waveform diagram of the input and output terminals of the embodiment of the present disclosure;

[0036] Figure 8 1 is a waveform diagram of the DAB leakage inductance and the current of the SRC resonant cavity according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0037] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0038] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present disclosure belongs.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] Example 1

[0041] In one embodiment of the present disclosure, a hybrid ISOP DC transformer soft-start current limiting control method is provided, which can accurately limit the inrush current of the hybrid ISOP DC transformer during startup without the need for a resonant cavity voltage or current sensor, balance the input terminal capacitor voltage, shorten the response time, make the output voltage reach the set value smoothly and reduce overshoot, and reduce the cost and implementation difficulty, including:

[0042] Step 1: In the input series output parallel ISOP topology, obtain the operating status data of the dual active bridge converter and the series resonant converter, as well as the output voltage and output current of the ISOP DC transformer;

[0043] Step 2: According to the working state data of the dual active bridge converter, calculate the peak value of the leakage inductance current of the dual active bridge converter and the average current of the secondary side of the transformer under the current phase shift parameters; use Kirchhoff's law and the relationship between capacitor voltage and current to analyze the relationship between the total output current of the hybrid ISOP DC transformer and the output current of the dual active bridge converter and the output current of the series resonant converter; construct an extended state observer to estimate the average current of the secondary side of the transformer of the series resonant converter;

[0044] Step 3: Estimate the peak voltage of the resonant capacitor in one switching cycle based on the average current value of the secondary side of the transformer of the series resonant converter, the capacitance of the resonant capacitor, the transformer ratio, and the switching frequency; Estimate the resonant cavity peak current of the SRC at the current duty cycle based on the input voltage, output voltage, transformer ratio, resonant inductance and resonant capacitor parameters of the SRC, and the estimated resonant capacitor voltage peak value;

[0045] Step 4: Under the condition that the peak current of the leakage inductance of the dual active bridge converter is ensured to be less than the set current limit value, the internal shift phase ratio or the single shift phase ratio of the dual active bridge converter is adjusted by the PI controller to control the input side capacitor voltage of the hybrid ISOP DC transformer to be close to the reference value. At the same time, the duty cycle of the series resonant converter is adjusted. When the duty cycle of the series resonant converter increases to the set value, the output voltage of the hybrid ISOP DC transformer reaches the set value, and the startup process ends.

[0046] As an embodiment, the hybrid ISOP DC transformer soft start current limiting control method disclosed in the present invention is based on the topology of the hybrid ISOP DC transformer, such as Figure 1 As shown, the specific process of implementing the hybrid ISOP DC transformer soft start current limiting control method using the hybrid ISOP DC transformer topology is as follows:

[0047] Step 1: In an input series output parallel ISOP topology, obtain the working state data of the dual active bridge converter and the series resonant converter, as well as the output voltage and output current of the ISOP DC transformer, including obtaining the working state data of the dual active bridge converter and the series resonant converter, wherein the working state data of the dual active bridge converter includes leakage inductance and transformer ratio, and the working state data of the series resonant converter includes resonant capacitance value, resonant inductance value, transformer ratio and switch operating frequency, and obtain the dual active bridge converter input voltage, the series resonant converter input voltage and the ISOP DC transformer output voltage and output current through voltage and current sensors in each control cycle; and calculate the series resonant converter input voltage under rated conditions.

[0048] Specifically, the inductance value L of DAB is measured in advance. k , Transformer ratio n DAB, the resonant inductor L of SRC r , resonant capacitor C r , Transformer ratio n SRC and the switching frequency f s In each control cycle, the voltage and current sensor detects the input voltage V of DAB. C1 , SRC input voltage V C2 , the output voltage V of the hybrid ISOP DC transformer out , load current I out , calculate the expected SRC input voltage at rated conditions:

[0049] V inSRC_ref =n SRC V o_ref (1)

[0050] Among them, V o_ref It is the output voltage of ISOP DC transformer under rated condition.

[0051] Furthermore, SRC adopts open-loop control, responsible for transmitting most of the power and ensuring transmission efficiency; DAB adopts closed-loop control, transmitting a small part of the power, responsible for controlling the transmission power and avoiding overvoltage on the input capacitors C1 and C2.

[0052] Step 2: According to the working state data of the dual active bridge converter, calculate the leakage inductance current value and the leakage inductance current peak value of the dual active bridge converter under the current phase shift parameters; use Kirchhoff's law and the relationship between capacitor voltage and current to analyze the total output current I of the hybrid ISOP DC transformer out The relationship between the output current of the dual active bridge converter and the output current of the series resonant converter is constructed; an extended state observer is constructed to estimate the average current of the secondary side of the transformer of the series resonant converter;

[0053] Specifically, according to the DAB input voltage V C1 , output voltage V out , inductance parameter L k and transformer ratio n DAB , calculate the leakage inductance peak current I of DAB under the current phase shift parameters p_DAB And the average current I DAB .

[0054]

[0055]

[0056] Among them, f s is the switching operating frequency, d = n DAB V out / V C1, d is the normalized input-output voltage ratio of DAB, D IPS is the internal phase shift modulation parameter of DAB, D SPS It is the single phase shift modulation parameter of DAB.

[0057] Furthermore, Kirchhoff's law and the relationship between capacitor voltage and current are used to analyze the total output current I of the hybrid ISOP DC transformer. out The relationship between the output current of the dual active bridge converter and the output current of the series resonant converter;

[0058] Specifically, Figure 4 According to Kirchhoff's law and the relationship between capacitor voltage and current, the current flowing through node E has the following relationship:

[0059]

[0060] Rewrite the above formula as

[0061]

[0062] Among them I od =I DAB -I out , f is the total uncertain disturbance. Let z1 be the predicted value of the state observer for the output voltage of the ISOP DC transformer, and z2 be the predicted value of the state observer for the total uncertain disturbance. Then the prediction errors e1 and e2 of the observer are

[0063]

[0064] Furthermore, we construct a first-order extended state observer

[0065]

[0066] Where β1 and β2 are observer error coefficients. When the error e1 is equal to 0, the observer model in equation (7) is close to the actual model in equation (5). In order to analyze the observation error, it is necessary to construct a state space function. From equations (6) and (7), we can get

[0067]

[0068] In state space, it can be expressed as

[0069]

[0070] If the observer error coefficients β1 and β2 are strictly positive, then the roots of the characteristic polynomial of A are all located in the left half plane of the s plane, satisfying the Routh-Hurwitz stability criterion, so the prediction error will approach 0 infinitely. For a first-order extended state observer, the coefficients β1 and β2 are 2ωn and ω n 2 , coefficient ω n represents the bandwidth of the observer. Bandwidth ω n The value of determines the performance of the observer. n The larger the value of is, the higher the prediction accuracy of the observer will be. n As the bandwidth increases, the noise sensitivity of the observer will also increase. Therefore, when setting the bandwidth, attention should be paid to balancing the accuracy and noise sensitivity of the observer. n The selection method is: n is set to about 1 / 3 of the SRC resonant frequency. In this embodiment, the SRC resonant frequency f r =15kHz, then ω n =1 / 3f r =31415rad / s, which not only ensures the prediction accuracy but also suppresses the noise sensitivity of the predictor.

[0071] To facilitate implementation in a microcontroller, the observer is discretized using the forward Euler formula as

[0072]

[0073] Where T s is a control cycle. From formula (5), the average current expression of the SRC secondary side corresponding to the k+1th control cycle is:

[0074] I sec (k+1)=z2(k+1) / p (12)

[0075] Step 3: Based on the average current value I of the secondary side of the transformer of the series resonant converter sec , resonant capacitor value C r , Transformer ratio n SRC , switching frequency f s Estimate the peak voltage of the resonant capacitor in a switching cycle; based on the input voltage, output voltage, transformer ratio, resonant inductor and resonant capacitor parameters of SRC, and the estimated resonant capacitor voltage peak value V cr_p , and then estimate the peak current I of the resonant cavity of SRC at the current duty cycle p ;

[0076] Specifically, the peak voltage of the resonant capacitor in one switching cycle can be expressed as

[0077]

[0078] Figure 5It is the waveform of the voltage measurement value and the voltage peak estimated value of the resonant capacitor in the simulation experiment. It can be seen that this method can estimate the peak voltage of the resonant capacitor very accurately, which is convenient for further observing the peak current of the current resonant cavity.

[0079] Further, according to the input voltage, output voltage, transformer ratio, resonant inductance and resonant capacitance parameters of SRC, and the estimated resonant capacitor voltage peak value V cr_p , and then estimate the peak current I of the resonant cavity of SRC at the current duty cycle p ; Figure 6 It is the phase trajectory diagram of the SRC resonant cavity when the output voltage is close to 0 during the startup process. According to the phase trajectory diagram and the working characteristics of SRC, the peak current expression of the SRC resonant cavity is obtained.

[0080]

[0081] in,

[0082]

[0083] Among them, I Amp is the maximum amplitude of the SRC resonant cavity current.

[0084] Step 4: Under the condition that the peak current of the leakage inductance of the dual active bridge converter is ensured to be less than the set current limit value, the internal shift phase ratio or the single shift phase ratio of the dual active bridge converter is adjusted by the PI controller to control and adjust the input side capacitor voltage of the hybrid ISOP DC transformer to be close to the reference value. At the same time, the duty cycle of the series resonant converter is adjusted. When the duty cycle of the series resonant converter increases to the set value, the output voltage of the hybrid ISOP DC transformer reaches the set value, and the startup process ends;

[0085] Specifically: To ensure the peak value of DAB leakage inductance current I p_DAB When the current is less than the set current limit value, the PI controller adjusts the internal shift of DAB to D IPS Or single shift comparison D SPS , so that the capacitor voltage V C2 Close to the reference value V inSRC_ref If the DAB leakage inductance current is greater than the set current limit, D IPS or D SPS At the same time, while ensuring the current resonant cavity peak current I p When the current is less than the set current limit value, slowly increase the duty cycle D of SRC SRC If the SRC resonant cavity peak current is greater than the set current limit, D SRC constant. Figure 7 is the input capacitor voltage V of DAB and SRC during startupC1 、V C2 And the output voltage V out As shown in the waveform diagram, each voltage reaches the set reference value smoothly without overshoot. Figure 8 The waveforms of the DAB leakage inductance and the SRC resonant cavity current during the startup process are precisely limited to the set current limit value. When the duty cycle of the SRC increases to 0.5, the output voltage of the hybrid ISOP DC transformer reaches near the set value, and the startup process ends.

[0086] Example 2

[0087] In one embodiment of the present disclosure, a hybrid ISOP DC transformer soft start current limiting control system is provided, comprising:

[0088] A data acquisition module is used to acquire the working state data of the dual active bridge converter and the series resonant converter, as well as the output voltage and output current of the ISOP DC transformer in the input series output parallel ISOP topology structure;

[0089] The calculation module is used to calculate the peak current of the leakage inductance of the dual active bridge converter and the average current of the secondary side of the transformer under the current phase shift parameters according to the working state data of the dual active bridge converter; according to the output voltage and output current of the hybrid ISOP DC transformer, the relationship between the total output current of the ISOP DC transformer and the output current of the dual active bridge converter and the output current of the series resonant converter is analyzed by using Kirchhoff's law and the relationship between capacitor voltage and current to construct an extended state observer, and estimate the average current of the secondary side of the transformer of the series resonant converter; according to the average current value of the secondary side of the transformer of SRC, the capacitance value of the resonant capacitor, the transformer ratio, and the switching frequency, calculate the peak voltage of the resonant capacitor in one switching cycle; according to the input voltage, output voltage, transformer ratio, resonant inductance and resonant capacitor parameters of SRC, and the estimated resonant capacitor voltage peak value, obtain the resonant cavity peak current of the series resonant converter under the current duty cycle;

[0090] The control current limiting module is used to adjust the internal shift phase ratio or the single shift phase ratio of the dual active bridge converter through the PI controller while ensuring that the peak current of the leakage inductance of the dual active bridge converter is less than the set current limit value, so as to control and adjust the input side capacitor voltage of the hybrid ISOP DC transformer to be close to the reference value, and at the same time, adjust the duty cycle of the series resonant converter. When the duty cycle of the series resonant converter increases to the set value, the output voltage of the hybrid ISOP DC transformer reaches the set value, and the startup process ends.

[0091] Example 3

[0092] In one embodiment of the present disclosure, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the hybrid ISOP DC transformer soft-start current limiting control method is implemented.

[0093] Example 4

[0094] In one embodiment of the present disclosure, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the hybrid ISOP DC transformer soft-start current limiting control method is implemented.

[0095] Example 5

[0096] In one embodiment of the present disclosure, an electronic device is provided, including: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device executes the hybrid ISOP DC transformer soft-start current limiting control method.

[0097] The present disclosure is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present disclosure. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0098] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0099] Although the above describes the specific implementation methods of the present disclosure in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present disclosure. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present disclosure, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present disclosure.

Claims

1. A hybrid ISOP DC transformer soft-start current limiting control method, characterized in that: include: In the input series output parallel ISOP topology, obtain the operating status data of the dual active bridge converter and the series resonant converter, as well as the output voltage and output current of the ISOP DC transformer; According to the working state data of the dual active bridge converter, the peak current of the leakage inductance of the dual active bridge converter and the average current of the secondary side of the transformer under the current phase shift parameters are calculated; Kirchhoff's law and the relationship between capacitor voltage and current are used to analyze the relationship between the total output current of the ISOP DC transformer and the output current of the dual active bridge converter and the output current of the series resonant converter. An extended state observer is constructed to estimate the average current of the transformer secondary side of the series resonant converter. According to the average current value of the secondary side of the SRC transformer, the capacitance of the resonant capacitor, the transformer ratio, and the switching frequency, the peak voltage of the resonant capacitor in one switching cycle is calculated; according to the input voltage, output voltage, transformer ratio, resonant inductance and resonant capacitor parameters of the SRC, and the estimated resonant capacitor voltage peak value, the resonant cavity peak current of the series resonant converter at the current duty cycle is obtained; Under the condition that the leakage inductance current of the dual active bridge converter is ensured to be less than the set current limit value, the input side capacitor voltage of the hybrid ISOP DC transformer is controlled and adjusted to be close to the reference value by adjusting the internal shift phase ratio or the single shift phase ratio of the dual active bridge converter. At the same time, the duty cycle of the series resonant converter is adjusted. When the duty cycle of the series resonant converter increases to the set value, the output voltage of the hybrid ISOP DC transformer reaches the set value, and the startup process ends.

2. The hybrid ISOP DC transformer soft-start current limiting control method according to claim 1, characterized in that: The working state data of the dual active bridge converter and the series resonant converter are obtained, wherein the working state data of the dual active bridge converter includes leakage inductance and transformer ratio, and the working state data of the series resonant converter includes resonant capacitance value, resonant inductance value, transformer ratio and switch operating frequency. The input voltage of the dual active bridge converter, the input voltage of the series resonant converter and the output voltage and output current of the ISOP DC transformer are obtained through voltage and current sensors in each control cycle; and the input voltage of the series resonant converter under rated working conditions is calculated.

3. The hybrid ISOP DC transformer soft-start current limiting control method according to claim 1, characterized in that: According to the input voltage V of the dual active bridge converter C1 , output voltage V out , inductance parameter L k and transformer ratio n DAB , calculate the current phase shift parameter D SPS or D IPS In this case, the peak current of the leakage inductance of the dual active bridge converter I p_DAB and the average secondary current I DAB .

4. The hybrid ISOP DC transformer soft-start current limiting control method according to claim 1, characterized in that: Using Kirchhoff's law and the relationship between capacitor voltage and current to analyze the total output current I of the hybrid ISOP DC transformer out The relationship between the output current of the dual active bridge converter and the output current of the series resonant converter is used to construct an extended state observer. The 1 / 3 resonant frequency value is used as the observer bandwidth to calculate the average secondary current of the transformer of the series resonant converter. According to the average secondary current value of the transformer of the series resonant converter I sec , resonant capacitor value C r , Transformer ratio n SRC , switching frequency f s Estimate the peak voltage of the resonant capacitor during one switching cycle.

5. The hybrid ISOP DC transformer soft-start current limiting control method according to claim 1, characterized in that: According to the input voltage, output voltage, transformer ratio, resonant inductance and resonant capacitance parameters of the series resonant converter, and the estimated resonant capacitor voltage peak value, the resonant cavity peak current of the series resonant converter under the current duty cycle is estimated. Under the condition that the leakage inductance peak current of the dual active bridge converter is less than the set current limit value, the internal shift phase D of the dual active bridge converter is adjusted by the PI controller. IPS Or single shift comparison D SPS , so that the capacitor voltage V C2 Close to the reference value, at the same time, while ensuring that the current resonant cavity peak current is less than the set current limit value, slowly increase the duty cycle of the series resonant converter. When the duty cycle of the series resonant converter increases to the set value, the output voltage of the hybrid ISOP DC transformer reaches the set value, and the startup process ends.

6. Hybrid ISOP DC transformer soft start current limiting control system, characterized in that: include: A data acquisition module is used to acquire the working state data of the dual active bridge converter and the series resonant converter, as well as the output voltage and output current of the ISOP DC transformer in the input series output parallel ISOP topology structure; A calculation module, used for calculating the peak current of the leakage inductance of the dual active bridge converter and the average current of the secondary side of the transformer under the current phase shift parameters according to the working state data of the dual active bridge converter; Kirchhoff's law and the relationship between capacitor voltage and current are used to analyze the relationship between the total output current of the ISOP DC transformer and the output current of the dual active bridge converter and the output current of the series resonant converter, and an extended state observer is constructed to estimate the average current of the secondary side of the transformer of the series resonant converter; based on the average current value of the secondary side of the SRC transformer, the capacitance of the resonant capacitor, the transformer ratio, and the switching frequency, the peak voltage of the resonant capacitor in a switching cycle is calculated; based on the input voltage, output voltage, transformer ratio, resonant inductance and resonant capacitor parameters of the SRC, and the estimated resonant capacitor voltage peak, the resonant cavity peak current of the series resonant converter at the current duty cycle is obtained; The control current limiting module is used to adjust the inner shift phase ratio or the single shift phase ratio of the dual active bridge converter through the PI controller while ensuring that the peak current of the leakage inductance of the dual active bridge converter is less than the set current limit value, so as to control and adjust the capacitor voltage on the input side of the series resonant converter to be close to the reference value, and at the same time, adjust the duty cycle of the series resonant converter. When the duty cycle of the series resonant converter increases to the set value, the output voltage of the hybrid ISOP DC transformer reaches the set value, and the startup process ends.

7. The hybrid ISOP DC transformer soft start current limiting control system as claimed in claim 6, characterized in that: Using Kirchhoff's law and the relationship between capacitor voltage and current to analyze the total output current I of the hybrid ISOP DC transformer out The relationship between the output current of the dual active bridge converter and the output current of the series resonant converter is used to construct an extended state observer. The 1 / 3 resonant frequency value is used as the observer bandwidth to calculate the average secondary current of the transformer of the series resonant converter. According to the average secondary current value of the transformer of the series resonant converter I sec , resonant capacitor value C r , Transformer ratio n SRC , switching frequency f s Estimate the peak voltage of the resonant capacitor during one switching cycle.

8. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the hybrid ISOP DC transformer soft-start current limiting control method according to any one of claims 1 to 6 is implemented.

9. A non-transitory computer-readable storage medium, characterized in that: The non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by the processor, the hybrid ISOP DC transformer soft-start current limiting control method as described in any one of claims 1 to 6 is implemented.

10. An electronic device, characterized in that: include: A processor, a memory and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory so that the electronic device executes the hybrid ISOP DC transformer soft-start current limiting control method as described in any one of claims 1 to 6.

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