Hybrid isop dc transformer soft start current limiting control method and system

Abstract

The disclosure provides a hybrid ISOP DC transformer soft-start current-limiting control method and system, relates to the technical field of power conversion control, and comprises the following steps: in an input series output parallel ISOP topology structure, according to working state data of a 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 are calculated; by using the Kirchhoff law and the relationship between the capacitor voltage and the current, an extended state observer is constructed to estimate the average current of the secondary side of the transformer of the series resonant converter; the peak current of the resonant cavity of the series resonant converter under the current duty cycle is obtained; under the condition that the leakage inductance current of the dual active bridge converter is less than the set current limiting value, the input side capacitor voltage of the series resonant converter is controlled to be close to the reference value by adjusting the inner phase shift ratio or the single phase shift ratio of the DAB; the duty cycle of the series resonant converter is adjusted until the output voltage of the hybrid ISOP DC transformer reaches the set value, and the starting process is completed.

Description

Technical Field

[0001] This disclosure relates to the field of power conversion control technology, specifically to a soft-start current limiting control method and system for hybrid ISOP DC transformers. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] As a core device in the energy internet, the power router plays a vital role in utilizing renewable energy, managing energy flow, and improving grid stability. Given the numerous voltage / power levels of various DC "source-load-storage" systems, power routers employing a dual DC bus structure offer advantages in cost, efficiency, and the number of conversion poles. The bidirectional isolation DC transformer connecting the dual DC buses becomes the core component of the power router.

[0004] Among various DC transformers, the highly efficient Series Resonant Converter (SRC) and the Dual-Active Bridge (DAB) converter, which offers easy power control, are two of the most commonly used topologies. They are often combined in an Input-Series-Output-Parallel (ISOP) topology, which combines the advantages of both, offering high flexibility, high efficiency, and high reliability, and has broad application prospects.

[0005] However, hybrid ISOP DC transformers suffer from the disadvantages of both DAB and SRC topologies, as well as their coupling effects, leading to problems such as overcurrent, resonant capacitor overvoltage, switching device turn-off overvoltage, and input capacitor voltage imbalance during startup. In severe cases, this can even damage the devices. Currently, there is limited research on soft-start strategies for hybrid ISOP DC transformers.

[0006] Currently, there is a three-stage DC transformer startup precision 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 circuitry and voltage sensors to the resonant cavity of the SRC submodule, which increases the additional hardware cost of the system and also presents significant challenges in terms of feasibility. Summary of the Invention

[0007] To address the aforementioned issues, this disclosure proposes a soft-start current-limiting control method and system for hybrid ISOP DC transformers. This method eliminates the need for resonant cavity voltage or current sensors, limits the surge current during the startup process of the hybrid ISOP DC transformer, balances the input capacitor voltage, shortens the response time, ensures the output voltage reaches the set value smoothly, reduces overshoot, and lowers costs and implementation difficulty.

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

[0009] The soft-start current limiting control method for hybrid ISOP DC transformers includes:

[0010] In an ISOP topology with series input and parallel output, 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, are obtained.

[0011] Based on the operating status data of the dual active bridge converter, calculate the peak leakage inductance current of the dual active bridge converter and the average secondary current of the transformer under the current phase shift parameters; use Kirchhoff's laws and the relationship between capacitor voltage and current to analyze the relationship between the total output current of the hybrid ISOP DC transformer, 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 secondary current of the transformer in the series resonant converter.

[0012] The peak voltage of the resonant capacitor in one switching cycle is estimated based on the average secondary current of the transformer, the capacitance of the resonant capacitor, the transformer turns ratio, and the switching frequency of the series resonant converter. The peak current of the resonant cavity of the series resonant converter at the current duty cycle is obtained based on the input voltage, output voltage, transformer turns ratio, parameters of the resonant inductor and resonant capacitor, and the estimated peak voltage of the resonant capacitor.

[0013] While ensuring that the peak leakage inductance current of the dual active bridge converter is less than the set current limit, the inner shift ratio or single shift ratio of the dual active bridge converter is adjusted by the PI controller to control the input capacitor voltage of the hybrid ISOP DC transformer to approach 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] The hybrid ISOP DC transformer soft-start current limiting control system includes:

[0016] The data acquisition module is used to acquire 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 in the input series and output parallel ISOP topology.

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

[0018] The current limiting module is used to control the input capacitor voltage of the hybrid ISOP DC transformer to approach the reference value by adjusting the inner shift ratio or single shift ratio of the dual active bridge converter through the PI controller, while ensuring that the peak leakage inductance current of the dual active bridge converter is less than the set current limit value. At the same time, it adjusts 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 includes a computer program that, when executed by a processor, implements the hybrid ISOP DC transformer soft-start current limiting control method.

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

[0022] A non-transitory computer-readable storage medium is provided for storing computer instructions, which, when executed by a processor, implement the hybrid ISOP DC transformer soft-start current limiting control method.

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

[0024] An electronic device includes 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 to enable the electronic device to implement the hybrid ISOP DC transformer soft-start current limiting control method.

[0025] Compared with the prior art, the beneficial effects of this disclosure are as follows:

[0026] The hybrid ISOP DC transformer soft-start current limiting control method disclosed herein only requires measuring the input and output capacitor voltages and the load current. Using an extended state observer, the peak value of the leakage inductance current of the series resonant converter under the current duty cycle is calculated based on the circuit parameters. The peak current of the circuit can be monitored without adding extra 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 differentiating the output voltage.

[0027] The hybrid ISOP DC transformer soft-start current limiting control method disclosed herein requires a simple calculation process. While ensuring that the peak value of the DAB leakage inductance current is less than the set current limit, the method adjusts the inward shift ratio of DAB to D using a PI controller. IPS Or a single shift compared to D SPS This brings the input capacitor voltage of the hybrid ISOP DC transformer close to the reference value. Simultaneously, while ensuring the current peak current of the resonant cavity is less than the set current limit, the duty cycle D of the SRC is slowly increased. SRC 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. This process has low requirements for the controller performance. This disclosure can accurately limit the peak current, avoid device damage due to overcurrent, and at the same time ensure the power transmission of the converter and the startup speed. Attached Figure Description

[0028] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure.

[0029] Figure 1 This is the topology of the hybrid ISOP DC transformer according to an embodiment of this disclosure;

[0030] Figure 2 This is an implementation block diagram of an embodiment of this disclosure;

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

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

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

[0034] Figure 6 This is a state trajectory diagram of the SRC resonant cavity during startup according to an embodiment of this disclosure;

[0035] Figure 7 The following are voltage waveforms at the input and output terminals of an embodiment of this disclosure;

[0036] Figure 8 The diagram shows the current waveforms of the DAB leakage inductance and the SRC resonant cavity in an embodiment of this disclosure. Detailed Implementation

[0037] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0038] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] Example 1

[0041] One embodiment of this disclosure provides a soft-start current-limiting control method for a hybrid ISOP DC transformer. This method can precisely limit the inrush current during the startup process of a hybrid ISOP DC transformer without requiring resonant cavity voltage or current sensors, balance the input capacitor voltage, shorten the response time, ensure the output voltage smoothly reaches the set value, reduce overshoot, and lower costs and implementation difficulty. The method includes:

[0042] Step 1: In the ISOP topology with input series and output parallel, 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: Based on the operating status data of the dual active bridge converter, calculate the peak leakage inductance current of the dual active bridge converter and the average secondary current of the transformer under the current phase shift parameters; analyze the relationship between the total output current of the hybrid ISOP DC transformer, the output current of the dual active bridge converter, and the output current of the series resonant converter using Kirchhoff's laws and the relationship between capacitor voltage and current; construct an extended state observer to estimate the average secondary current of the transformer in 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 transformer secondary side, the capacitance value of the resonant capacitor, the transformer turns ratio, and the switching frequency of the series resonant converter; and estimate the peak current of the resonant cavity of the SRC under the current duty cycle based on the input voltage, output voltage, transformer turns ratio, resonant inductor and resonant capacitor parameters of the SRC, and the estimated peak voltage of the resonant capacitor.

[0045] Step 4: While ensuring that the peak leakage inductance current of the dual active bridge converter is less than the set current limit, adjust the inner shift ratio or single shift ratio of the dual active bridge converter through the PI controller to control the input capacitor voltage of the hybrid ISOP DC transformer to approach the reference value. 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.

[0046] As one embodiment, the soft-start current limiting control method for hybrid ISOP DC transformers disclosed herein is based on the topology of hybrid ISOP DC transformers, such as... Figure 1 As shown, the specific process of implementing the soft-start current limiting control method for a hybrid ISOP DC transformer using a hybrid ISOP DC transformer topology is as follows:

[0047] Step 1: In the input-series-output-parallel ISOP topology, acquire 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. This includes acquiring the operating status data of the dual active bridge converter and the series resonant converter. The operating status data of the dual active bridge converter includes leakage inductance and transformer turns ratio, while the operating status data of the series resonant converter includes resonant capacitance, resonant inductance, transformer turns ratio, and switching frequency. In each control cycle, 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 acquired through voltage and current sensors. The input voltage of the series resonant converter under rated operating conditions is then calculated.

[0048] Specifically, the inductance value L of DAB is measured in advance. k Transformer turns ratio n DABThe resonant inductance L of SRC r Resonant capacitor C r Transformer turns ratio n SRC and switching operating frequency f s Each control cycle detects the input voltage V of the DAB via voltage and current sensors. C1 The input voltage V of SRC C2 The output voltage V of the hybrid ISOP DC transformer out Load current I out Calculate the expected SRC input voltage under rated operating conditions:

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

[0050] Among them, V o_ref This is the output voltage of the ISOP DC transformer under rated operating conditions.

[0051] Furthermore, SRC uses open-loop control to transmit most of the power and ensure transmission efficiency; DAB uses closed-loop control to transmit a small portion of the power and is responsible for controlling the transmitted power to prevent overvoltage from occurring in the input capacitors C1 and C2.

[0052] Step 2: Based on the operating status data of the dual active bridge converter, calculate the leakage inductance current value and peak value of the dual active bridge converter under the current phase shift parameters; analyze the total output current I of the hybrid ISOP DC transformer using Kirchhoff's laws and the relationship between capacitor voltage and current. out The relationship between the output current of the dual active bridge converter and the output current of the series resonant converter is established; an extended state observer is constructed to estimate the average secondary current of the transformer in the series resonant converter.

[0053] Specifically, based on the input voltage V of the DAB C1 Output voltage V out Inductance parameter L k and transformer turns ratio n DAB Calculate the peak leakage inductance current I of DAB under the current phase shift parameters. p_DAB and the average secondary current I of the transformer DAB .

[0054]

[0055]

[0056] Among them, f s The switching operating frequency is d = n DAB V out / V C1d is the normalized input-output voltage ratio of DAB, D IPS D represents the internal phase-shift modulation parameter of DAB. SPS These are the single-phase-shift modulation parameters for DAB.

[0057] Furthermore, the total output current I of the hybrid ISOP DC transformer is analyzed using Kirchhoff's laws and the relationship between capacitor voltage and current. out The relationship between the output current of the dual active bridge converter and the output current of the series resonant converter;

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

[0059]

[0060] Rewrite the above equation as follows:

[0061]

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

[0063]

[0064] Furthermore, a first-order extended state observer is constructed.

[0065]

[0066] Where β1 and β2 are the observer error coefficients, when the error e1 equals 0, the observer model in equation (7) is close to the actual model in equation (5). To analyze the observation error, a state-space function needs to be constructed, which can be obtained from equations (6) and (7).

[0067]

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

[0069]

[0070] If the observer error coefficients β1 and β2 are strictly positive, then all roots of the characteristic polynomial of A lie in the left half of the s-plane, satisfying the Routh-Hurwitz stability criterion. Therefore, the prediction error will approach 0 infinitely. For a first-order extended state observer, the coefficients β1 and β2 are 2ω...n and ω n 2 coefficient ω n This represents the bandwidth of the observer. Bandwidth ω n The value of ω determines the performance of the observer. n A larger value for ω results in higher prediction accuracy for the observer. However, as ω... n As the bandwidth increases, the observer's noise sensitivity also increases. Therefore, when setting the bandwidth, attention should be paid to balancing the observer's accuracy and noise sensitivity. n The selection method is as follows: ω n The resonant frequency of the SRC is set to approximately 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 ensures prediction accuracy while suppressing the noise sensitivity of the predictor.

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

[0072]

[0073] Where T s This is one control cycle. From equation (5), the expression for the average SRC secondary current corresponding to the (k+1)th control cycle is:

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

[0075] Step 3: Based on the average secondary current value I of the transformer in the series resonant converter. sec The capacitance value C of the resonant capacitor r Transformer turns ratio n SRC Switching frequency f s Estimate the peak voltage of the resonant capacitor during one switching cycle; based on the input voltage, output voltage, transformer turns ratio, resonant inductance and resonant capacitor parameters of the SRC, and the estimated peak voltage V of the resonant capacitor. cr_p Then estimate the peak resonant current I of SRC at the current duty cycle. p ;

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

[0077]

[0078] Figure 5The waveforms show the measured voltage and estimated peak voltage 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 facilitates further observation of the peak current of the current resonant cavity.

[0079] Furthermore, based on the input voltage, output voltage, transformer turns ratio, resonant inductance and resonant capacitor parameters of the SRC, and the estimated peak voltage V of the resonant capacitor... cr_p Then estimate the peak resonant current I of SRC at the current duty cycle. p ; Figure 6 This is the phase trajectory diagram of the SRC resonant cavity when the output voltage is close to 0 during startup. Based on the phase trajectory diagram and the operating characteristics of the SRC, the expression for the peak current of the SRC resonant cavity is obtained.

[0080]

[0081] in,

[0082]

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

[0084] Step 4: While ensuring that the peak leakage inductance current of the dual active bridge converter is less than the set current limit, adjust the inner shift ratio or single shift ratio of the dual active bridge converter through the PI controller to control the input capacitor voltage of the hybrid ISOP DC transformer to approach the reference value. 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.

[0085] Specifically: ensuring the peak value of the DAB leakage inductance current I p_DAB When the current is less than the set current limit, the PI controller adjusts the inward shift of DAB relative to D. IPS Or a single shift compared to D SPS This causes the input capacitor voltage V of the SRC submodule to... C2 Approximately reference value V inSRC_ref If the leakage inductance current of DAB is greater than the set current limit, then D remains unchanged. IPS Or D SPS Unchanged. Meanwhile, while ensuring the current peak current I of the resonant cavity... p If the current is less than the set current limit, slowly increase the duty cycle D of SRC. SRC If the peak current of the SRC resonant cavity exceeds the set current limit, then D remains unchanged. SRC constant. Figure 7 It is the input capacitor voltage V of DAB and SRC during startup.C1 V C2 and output voltage V out The waveforms show that all voltages have reached the set reference values ​​smoothly without overshoot. Figure 8 These are the current waveforms of the DAB leakage inductance and the SRC resonant cavity during startup, both of which are precisely limited within the set current limit values. 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] One embodiment of this disclosure provides a hybrid ISOP DC transformer soft-start current limiting control system, comprising:

[0088] The data acquisition module is used to acquire 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 in the input series and output parallel ISOP topology.

[0089] The calculation module is used to calculate the peak leakage inductance current and average secondary current of the dual active bridge converter under the current phase shift parameters, based on the operating state data of the dual active bridge converter. Based on the output voltage and current of the hybrid ISOP DC transformer, it uses Kirchhoff's laws and the relationship between capacitor voltage and current to analyze the relationship between the total output current of the ISOP DC transformer, the output current of the dual active bridge converter, and the output current of the series resonant converter, constructing an extended state observer to estimate the average secondary current of the series resonant converter. Based on the average secondary current value of the transformer in the SRC, the resonant capacitor value, the transformer turns ratio, and the switching frequency, it calculates the peak voltage of the resonant capacitor in one switching cycle. Based on the input voltage, output voltage, transformer turns ratio, resonant inductance and resonant capacitor parameters of the SRC, and the estimated peak voltage of the resonant capacitor, it obtains the peak resonant cavity current of the series resonant converter under the current duty cycle.

[0090] The current limiting module is used to control the input capacitor voltage of the hybrid ISOP DC transformer to approach the reference value by adjusting the inner shift ratio or single shift ratio of the dual active bridge converter through the PI controller, while ensuring that the peak leakage inductance current of the dual active bridge converter is less than the set current limit value. At the same time, it adjusts 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] One embodiment of this disclosure provides a computer program product, including a computer program that, when executed by a processor, implements the hybrid ISOP DC transformer soft-start current limiting control method.

[0093] Example 4

[0094] One embodiment of this disclosure provides a non-transitory computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the hybrid ISOP DC transformer soft-start current limiting control method.

[0095] Example 5

[0096] One embodiment of this disclosure provides an electronic device, 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 to enable the electronic device to implement the hybrid ISOP DC transformer soft-start current limiting control method.

[0097] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. 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, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0098] 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.

[0099] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. A soft-start current-limiting control method for a hybrid ISOP DC transformer, characterized in that, include: In an ISOP topology with series input and parallel output, 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, are obtained. Based on the operating status data of the dual active bridge converter, calculate the peak leakage inductance current and the average secondary current of the transformer under the current phase shift parameters. By using Kirchhoff's laws and the relationship between capacitor voltage and current, the relationship between the total output current of the ISOP DC transformer, the output current of the dual active bridge converter, and the output current of the series resonant converter is analyzed. An extended state observer is constructed to estimate the average secondary current of the transformer in the series resonant converter. Based on the average secondary current of the transformer in the SRC, the capacitance of the resonant capacitor, the transformer turns ratio, and the switching frequency, calculate the peak voltage of the resonant capacitor in one switching cycle; based on the input voltage, output voltage, transformer turns ratio, resonant inductance and resonant capacitor parameters of the SRC, and the estimated peak voltage of the resonant capacitor, obtain the peak current of the resonant cavity of the series resonant converter under the current duty cycle. While ensuring that the leakage inductance current of the dual active bridge converter is less than the set current limit, the input capacitor voltage of the hybrid ISOP DC transformer is controlled to approach the reference value by adjusting the inner shift ratio or single shift 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 as described in claim 1, characterized in that, The system acquires the operating status data of the dual active bridge converter and the series resonant converter. The operating status data of the dual active bridge converter includes leakage inductance and transformer turns ratio, while the operating status data of the series resonant converter includes resonant capacitance, resonant inductance, transformer turns ratio, and switching frequency. In each control cycle, the system acquires 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 through voltage and current sensors. The system also calculates the input voltage of the series resonant converter under rated operating conditions.

3. The hybrid ISOP DC transformer soft-start current limiting control method as described in claim 1, characterized in that, Based on the input voltage V of the dual active bridge converter C1 Output voltage V out Inductance parameter L k and transformer turns ratio n DAB Calculate the current phase shift parameter D SPS Or D IPS Under these conditions, the peak leakage inductance current I of the dual active bridge converter p_DAB and the average current I on the secondary side of the transformer DAB .

4. The hybrid ISOP DC transformer soft-start current limiting control method as described in claim 1, characterized in that, Analyzing the total output current I of a hybrid ISOP DC transformer using Kirchhoff's laws and the relationship between capacitor voltage and current. out Based on the relationship between the output current of the dual active bridge converter and the output current of the series resonant converter, an extended state observer is constructed. Using 1 / 3 of the resonant frequency as the observer bandwidth, the average secondary current of the transformer in the series resonant converter is calculated. Based on the average secondary current value I of the transformer in the series resonant converter... sec The capacitance value C of the resonant capacitor r Transformer turns 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 as described in claim 1, characterized in that, Based on the input voltage, output voltage, transformer turns ratio, resonant inductor and capacitor parameters of the series resonant converter, and the estimated peak voltage of the resonant capacitor, the peak current of the resonant cavity of the series resonant converter at the current duty cycle is estimated. While ensuring that the peak leakage inductance current of the dual active bridge converter is less than the set current limit, the inner shift ratio of the dual active bridge converter, D, is adjusted via a PI controller. IPS Or a single shift compared to D SPS This causes the input capacitor voltage V of the series resonant converter to... C2 As the current approaches the reference value, while ensuring that the current peak current of the resonant cavity is less than the set current limit, the duty cycle of the series resonant converter is slowly increased. 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. A hybrid ISOP DC transformer soft-start current limiting control system, characterized in that, include: The data acquisition module is used to acquire 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 in the input series and output parallel ISOP topology. The calculation module is used to calculate the peak leakage inductance current and the average secondary current of the transformer under the current phase shift parameters, based on the operating status data of the dual active bridge converter. Using Kirchhoff's laws and the relationship between capacitor voltage and current, the relationship between the total output current of the ISOP DC transformer, the output current of the dual active bridge converter, and the output current of the series resonant converter is analyzed. An extended state observer is constructed to estimate the average secondary current of the transformer in the series resonant converter. Based on the average secondary current of the transformer in the SRC, the capacitance of the resonant capacitor, the transformer turns ratio, and the switching frequency, the peak voltage of the resonant capacitor in one switching cycle is calculated. Based on the input voltage, output voltage, transformer turns ratio, resonant inductor and resonant capacitor parameters of the SRC, and the estimated peak voltage of the resonant capacitor, the peak current of the resonant cavity of the series resonant converter at the current duty cycle is obtained. The current limiting module is used to control the input capacitor voltage of the series resonant converter to approach the reference value by adjusting the inner shift ratio or single shift 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. At the same time, it adjusts 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 described in claim 6, characterized in that, Analyzing the total output current I of a hybrid ISOP DC transformer using Kirchhoff's laws and the relationship between capacitor voltage and current. out Based on the relationship between the output current of the dual active bridge converter and the output current of the series resonant converter, an extended state observer is constructed. Using 1 / 3 of the resonant frequency as the observer bandwidth, the average secondary current of the transformer in the series resonant converter is calculated. Based on the average secondary current value I of the transformer in the series resonant converter... sec The capacitance value C of the resonant capacitor r Transformer turns 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 the processor, it implements the hybrid ISOP DC transformer soft-start current limiting control method according to any one of claims 1-6.

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

10. An electronic device, characterized in that, include: The device includes 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 to enable the electronic device to perform the hybrid ISOP DC transformer soft-start current limiting control method as described in any one of claims 1-6.

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