Interleaved burst mode operation control method for low ripple isop resonant converter

Abstract

The application discloses a kind of low ripple ISOP resonant converter interleaved burst mode operation control method, it is related to power electronic power conversion technical field, including: real-time acquisition ISOP resonant converter system output load power, lower than preset light load threshold then start interleaved burst mode, otherwise control each LLC module work in continuous resonance mode;According to load power and system peak efficiency power point, configure each module burst mode control parameter and conduction phase offset;Control each module is according to offset amount and is turned on in time, and works at resonant frequency and peak efficiency point during conduction period, and pauses power output during off period;Forced each module average burst switching function is equal, guarantee average power consistent and input voltage is divided;Disperse power output by time-sharing interleaved conduction, smooth capacitor charge-discharge, reduce output ripple;The application can effectively suppress output voltage ripple by interleaved operation while improving ISOP system light load operating efficiency by burst mode.

Description

Technical Field

[0001] This invention relates to the field of power electronic power conversion technology, specifically to an interleaved burst mode operation control method for a low-ripple ISOP resonant converter. Background Technology

[0002] With advancements in power electronics technology and the emergence of new application demands, medium- and high-voltage power conversion systems with large output currents are becoming increasingly important in modern power infrastructure. For example, medium-voltage direct current (MVDC) systems are widely used in renewable energy integration, offshore and submarine power transmission systems, and modern distribution network construction. MVDC distribution systems offer advantages such as high efficiency, long transmission distances, and high stability. Meanwhile, applications such as hydrogen production plants, data centers, and electric vehicle fast-charging stations typically require high-current power supplies with output currents reaching thousands of amperes. This continued growth in demand for high-voltage, high-current power places stringent requirements on the performance of power conversion structures and devices.

[0003] In DC-SST systems, the isolated DC-DC conversion stage is typically implemented using resonant converters. The LLC resonant converter, as a typical series resonant topology, achieves power transfer and electrical isolation through the cooperation of resonant capacitors and a high-frequency transformer. When operating near the resonant frequency, the LLC resonant converter can naturally achieve soft-switching operation over a wide load range. Its voltage gain mainly depends on the transformer turns ratio, thus requiring relatively simple control to operate and maintaining near-open-loop operation under specific conditions. These characteristics make the LLC resonant converter particularly suitable for ISOP-based DC-SST systems. Since the voltage gain is mainly determined by the transformer turns ratio, input voltage distribution between series LLC modules can be naturally achieved without additional voltage balancing circuitry.

[0004] However, in actual operation, maintaining high efficiency over a wide load range remains a major challenge for ISOP systems based on LLC resonant converters, especially under light load conditions where efficiency becomes increasingly critical. Under heavy load conditions, the efficiency of the power converter is mainly affected by the conduction losses of semiconductor devices and magnetic components; however, under light load conditions, switching losses, gate drive losses, and transformer core losses become the main sources of loss. Since these losses are largely independent of the load current, the power converter efficiency typically drops sharply when the load current falls below 10%-20% of the rated power.

[0005] To improve the light-load efficiency of resonant converters, burst mode (pulse mode) control is a widely adopted solution. In pulse mode, the converter periodically switches between on and off states: when on, the converter operates near its peak efficiency operating point, continuously supplying power to the load; while in the off state, the switching devices remain stationary, and the associated switching and drive losses are almost eliminated, thereby significantly improving the light-load efficiency.

[0006] However, existing burst-mode control schemes for ISOP systems generally adopt synchronous burst mode, where all modules are forced to perform instantaneous power equality, all burst switching functions are identical, and all modules turn on and off synchronously. While this scheme can ensure real-time equal distribution of module input voltage, it has inherent drawbacks: due to the synchronous switching of all modules, the output power is released in a highly concentrated manner during the conduction period, while during the turn-off period, no module participates in the output, resulting in a more intense charging and discharging process of the output capacitor, leading to a significant increase in output voltage ripple. Low-frequency voltage fluctuations generated by individual modules accumulate on the parallel output bus, amplifying bus ripple and increasing the stress on filter components, making it impossible to simultaneously achieve improved efficiency under light loads and stable output voltage. Summary of the Invention

[0007] The purpose of this invention is to provide an interleaved burst mode operation control method for a low-ripple ISOP resonant converter, so as to solve the problem that existing ISOP resonant converter synchronous burst mode light load control cannot simultaneously achieve light load efficiency improvement and output ripple suppression.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for interleaved burst mode operation control of a low-ripple ISOP resonant converter, wherein the ISOP resonant converter system includes N LLC resonant converter modules with identical structures, where N is a positive integer greater than or equal to 2; the input sides of all the LLC resonant converter modules are connected in series to form the high-voltage DC input terminal of the system, and the output sides of all the LLC resonant converter modules are connected in parallel to form the low-voltage DC output terminal of the system; each LLC resonant converter module adopts a half-bridge LLC resonant topology, including a half-bridge power switching unit, a resonant cavity composed of a resonant inductor and a resonant capacitor connected in series, a transformer with a magnetizing inductor, a rectifier unit, and an output filter capacitor; the control method includes the following steps:

[0009] S1. Real-time acquisition of the output load power of the ISOP resonant converter system. Determine the output load power Is the power level below the preset light load power threshold? If yes, activate the interleaved burst mode control; if no, control all LLC resonant converter modules to operate in continuous resonant mode.

[0010] S2. Based on the currently collected output load power Output power corresponding to the system's preset peak efficiency power point The burst mode core control parameters of each LLC resonant converter module are calculated and configured, and the burst conduction phase offset of each module is configured according to the number of modules N; the core control parameters include the burst conduction duration. Duration of sudden shutdown Sudden cycle, sudden duty cycle With burst frequency ;

[0011] S3. Control each LLC resonant converter module to perform burst conduction operation in a time-division manner according to the configured phase offset, so that a single LLC resonant converter module switches to operate independently in a very short time. During the conduction period, the switching frequency of the module is equal to the natural resonant frequency of the resonant cavity, and it operates at the peak efficiency power point. During the turn-off period, all switching devices of the half-bridge power switching unit of the module remain in the off state, and the power output is suspended.

[0012] S4. Force all the LLC resonant converter modules to have the same average burst switching function, so that the average output power of each module is always consistent, and ensure the average voltage balance of the input capacitors of each module, so as to meet the input voltage equalization requirement of ISOP architecture.

[0013] S5. By using the time-sharing and staggered operation mode of each module, the centralized power output is distributed to different time periods, smoothing the charging and discharging process of the output filter capacitor and reducing the system output voltage ripple.

[0014] Furthermore, in step S1, the light load power threshold is 10% to 20% of the rated output power of the ISOP resonant converter system.

[0015] Furthermore, in step S2, the burst period is the burst conduction duration. Duration of sudden shutdown The sum is expressed as:

[0016]

[0017]

[0018]

[0019] in, For sudden duty cycles, For burst frequencies, This is expressed as the output load power.

[0020] Furthermore, in step S2, the burst conduction phase offset of each module is 360° / N, so that the burst conduction periods of the N modules are evenly staggered within a burst cycle.

[0021] Furthermore, in step S3, the conduction timing of the three-pulse resonant conduction operation is divided into three consecutive sub-intervals, which are, in sequence, the initial excitation sub-interval. First active output sub-interval Second active output sub-interval The duration of the three sub-intervals is expressed as follows:

[0022]

[0023] in, This represents the inherent resonant frequency of the resonant cavity.

[0024] Further, in step S4, the average burst switching function is a module burst switching function S within a burst cycle. b The average value; the burst switching function S b The function representing the on or off state of the module is S when the module is on. b =1, S is turned off b =0; the average burst switching function of all modules is exactly the same, expressed as:

[0025]

[0026] in, ~ This is the average burst switching function for the 1st to Nth LLC resonant converter modules.

[0027] Furthermore, in step S4, the average output power of all modules remains consistent, satisfying the current distribution condition of the ISOP system, which is expressed as:

[0028]

[0029] in, ~ The average resonant current of the first to Nth LLC resonant converter modules is denoted by 〈・〉, which represents the average value within a burst cycle.

[0030] Further, in step S4, the input-side capacitor voltage of a single module is expressed as:

[0031]

[0032] in, For the module input side capacitor, Input current to the system, This represents the average value of the module's resonant current.

[0033] Further, in step S5, the system output voltage is expressed as:

[0034]

[0035] in, For the system output current, For system output filter capacitor, This is the module resonant current.

[0036] Compared with existing technologies, the present invention provides an interleaved burst mode operation control method for a low-ripple ISOP resonant converter. By abandoning the strong constraint of equal instantaneous power in synchronous burst mode, it only forces the average power of each module in the ISOP system to be equal. Through interleaved burst mode control, each module is turned on in a time-sharing manner. On the one hand, the output power of a single working module is increased to the peak efficiency point, maximizing the operating efficiency of the ISOP system under light load conditions. On the other hand, the concentrated power output is distributed to different time periods, smoothing the charging and discharging process of the output capacitor, significantly reducing output voltage ripple, and improving output voltage stability. At the same time, through the control of the constant average burst switching function, the average voltage of the input capacitor of each module is always balanced, meeting the core requirement of equal input voltage of the ISOP architecture, without compromising the system's operational stability, and taking into account the three core requirements of improving efficiency under light load, suppressing output ripple, and ensuring stable system operation. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0038] Figure 1 This is a schematic diagram of the overall topology of the ISOP resonant converter system applicable to the embodiments of the present invention.

[0039] Figure 2 The equivalent model of the burst mode circuit and the burst switching function S in the embodiments of the present invention. b A schematic diagram of the control relationship;

[0040] Figure 3 This is an equivalent circuit model diagram of the ISOP resonant converter system operating in interleaved burst mode in an embodiment of the present invention;

[0041] Figure 4 This is a graph showing the efficiency-load power characteristic of the LLC resonant converter in an embodiment of the present invention.

[0042] Figure 5 This is a schematic diagram of the runtime sequence of the interleaved (phase-shifting) burst mode in an embodiment of the present invention;

[0043] Figure 6 A schematic diagram of the actual results of the control signal and resonant current in the interleaved burst mode of this invention;

[0044] Figure 7 This is a waveform diagram showing the actual results of the input voltage (blue line) and output voltage (three interlaced lines of different colors) in the interlaced burst mode in this embodiment of the invention. Detailed Implementation

[0045] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0046] This embodiment provides an interleaved burst mode operation control method for a low-ripple ISOP resonant converter. First, the ISOP resonant converter system to which this method is applicable is described in detail:

[0047] As attached Figure 1 As shown, the ISOP resonant converter system comprises N structurally identical LLC resonant converter modules, where N is a positive integer greater than or equal to 2. The input sides of all LLC resonant converter modules are connected in series to form the system's high-voltage DC input terminal, which is connected to the medium-voltage DC bus. The output sides of all LLC resonant converter modules are connected in parallel to form the system's low-voltage DC output terminal, which supplies power to the load. This ISOP configuration effectively reduces the electrical and thermal stress of individual LLC resonant converter modules, making it possible to use low-voltage / low-current rated devices. It offers advantages such as simplified device selection, improved system reliability, and enhanced scalability, making it particularly suitable for high-power DC transformer (DC-SST) applications.

[0048] Each LLC resonant converter module adopts a half-bridge LLC resonant topology, including a half-bridge power switching unit (composed of power switches S1 and S2) and a resonant inductor. and resonant capacitor A resonant cavity composed of series connections, with a magnetizing inductor High-frequency transformer, rectifier unit and output filter capacitor The turns ratio of the primary to secondary side of the high-frequency transformer is n:1. S1 and S2 form a half-bridge inverter circuit. The rectifier unit is a half-bridge or full-bridge rectifier circuit. The output filter capacitor is... The load resistance is .

[0049] The inherent resonant frequency of the resonant cavity in the LLC resonant converter module Satisfying the formula:

[0050]

[0051] When the switching frequency of the LLC resonant converter module equal to the natural resonant frequency When the load is large, the LLC converter exhibits load-independent voltage gain characteristics. Its voltage gain is determined only by the turns ratio n of the primary and secondary sides of the transformer and is independent of the load size. It is particularly suitable for DC transformer (DCX) applications and can naturally achieve soft switching operation of switching devices over a wide load range, reducing conduction losses.

[0052] As attached Figure 4 As shown, traditional DC transformers based on LLC structures exhibit significant efficiency variations under different output power conditions, with peak efficiency typically occurring near the half-load point, which is the peak efficiency power point in this embodiment. However, under light load conditions, the efficiency drops sharply when the load gradually decreases to below 0.5 of the load point. This is because, under heavy load conditions, the efficiency of the LLC resonant converter is mainly affected by the conduction losses of semiconductor devices and magnetic components; while under light load conditions, switching losses, gate drive losses, and transformer core losses become the main sources of loss. These losses are largely independent of the load current, and when the load current drops below 10%-20% of the rated power, the converter efficiency drops sharply.

[0053] To address the issue of reduced efficiency under light loads, this embodiment employs a burst mode control strategy. Furthermore, to address the ripple amplification drawback of existing synchronous burst modes, interleaved burst mode control is used. The specific implementation steps are as follows:

[0054] Step 1: Real-time monitoring of load conditions

[0055] Real-time acquisition of output load power of ISOP resonant converter system Determine the output load power Is the power level below the preset light load power threshold? If yes, activate the interleaved burst mode control; if no, control all LLC resonant converter modules to operate in continuous resonant mode.

[0056] In this embodiment, the light load power threshold is 10% to 20% of the rated output power of the ISOP resonant converter system, which can be adjusted according to the efficiency requirements of the actual application scenario.

[0057] Step 2: Configuration of Control Parameters and Interleaved Timing

[0058] As attached Figure 2 As shown, based on the currently collected output load power Output power corresponding to the system's preset peak efficiency power point Calculate and configure the burst mode core control parameters for each LLC resonant converter module, and configure the burst conduction phase offset for each module according to the number of modules N.

[0059] Key control parameters include burst conduction duration Duration of sudden shutdown Sudden cycle, sudden duty cycle With burst frequency The burst cycle is the duration of the burst conduction. Duration of sudden shutdown The sum of the sudden duty cycles Burst frequency Average output load power They respectively satisfy the following formulas:

[0060]

[0061]

[0062]

[0063] According to the above formula, to minimize power loss during burst mode operation, the LLC resonant converter module must maintain its peak efficiency point throughout the conduction phase. Therefore, this embodiment adopts an optimized three-pulse switching mode, which achieves lower output voltage ripple while maintaining the best efficiency compared with the five-pulse and seven-pulse schemes.

[0064] In this embodiment, the burst conduction phase offset of each module is 360° / N, so that the burst conduction periods of the N modules are evenly staggered within a burst cycle, achieving time-division interleaved conduction. For example, when N=2, the conduction phases of the two modules are offset by 180°; when N=3, the conduction phases of the three modules are offset by 120° in sequence, and so on.

[0065] Step 3: Interleaved Burst Mode Operation Control

[0066] As attached Figure 5 As shown, each LLC resonant converter module is controlled to perform burst conduction operations in a time-division manner according to the configured phase offset, so that a single LLC resonant converter module switches to operation independently for a very short time. During the conduction period, the switching frequency of the module is equal to the natural resonant frequency of the resonant cavity. It operates at the peak efficiency power point; during the off-time period, all switching devices of the half-bridge power switching unit of the module remain off, suspending power output.

[0067] Based on the three-pulse burst mode operating waveform, the burst conduction operation performed by each module is a three-pulse resonant conduction operation, and its timing is divided into three consecutive sub-intervals, namely the initial excitation sub-interval. First active output sub-interval Second active output sub-interval The durations of the three sub-intervals satisfy the following formula:

[0068]

[0069] in, This represents the inherent resonant frequency of the resonant cavity.

[0070] Among them, the initial excitation sub-interval Within this phase, the resonant parameters of the LLC resonant converter module approach the steady-state value corresponding to the peak efficiency power point, but at this point, no active power is transferred to the output; subsequently, the first active output sub-interval... With the second active output sub-interval This constitutes the active power transfer phase, during which the converter operates at its resonant frequency. Working, output voltage It began to rise, due to and Together they correspond to a complete resonant cycle, and their operating frequency is equal to the resonant frequency. .

[0071] As attached Figure 6 As shown, during the sudden shutdown period, all switching devices of the LLC resonant converter module remain off, the switching action stops, and the switching loss and gate drive loss are almost completely eliminated, leaving only the fixed core loss that is independent of the load, thereby significantly improving the operating efficiency under light load conditions.

[0072] Step 4: Average Power Equalization and Input Voltage Balance Control

[0073] As attached Figure 3 As shown, the average burst switching function of all LLC resonant converter modules is forced to be completely equal, so that the average output power of each module is always consistent, ensuring the average voltage balance of the input capacitors of each module and meeting the input voltage equalization requirement of ISOP architecture.

[0074] First, the current distribution conditions of the ISOP system are derived: The current distribution conditions of the ISOP system can be derived through the equivalent model, and the equivalent output current of all modules satisfies the following:

[0075]

[0076] in, ~ This is the burst switching function for the 1st to Nth LLC resonant converter modules. ~ This represents the average resonant current of the first to Nth LLC resonant converter modules;

[0077] Using the relationship between resonant current and optimal power, this condition can be restated as:

[0078]

[0079] These relationships indicate that the current sharing in an ISOP system is determined by both the module's burst switching function and the module's input voltage.

[0080] In this embodiment, the system does not require that the instantaneous power of each module be equal, but only requires that the average power of each module be equal. This condition can be expressed as:

[0081]

[0082] in, ~ The average resonant current of the first to Nth LLC resonant converter modules is denoted by 〈・〉, which represents the average value within a burst cycle.

[0083] Correspondingly, the average burst switching function of all modules is forced to be exactly the same, satisfying the following formula:

[0084]

[0085] Wherein, the average burst switching function is the module burst switching function within a burst cycle. The average value; burst switching function A function characterizing the on / off state of a module; when the module is on... =1, when turned off =0.

[0086] Under these conditions, each module can operate using a different switching sequence, thereby achieving interleaved operation between modules. Although the instantaneous voltage and power of each module are not equal, their average values ​​remain consistent, ensuring reasonable current distribution in the ISOP system.

[0087] Taking the first module as an example, its input capacitor voltage is given by the following formula:

[0088]

[0089] in, For the module input side capacitor, Input current to the system, This represents the average resonant current of the modules. Since the switching functions are not perfectly consistent over time, the terms in the above equation will not immediately cancel each other out. Therefore, each module will experience alternating charge and discharge cycles based on its switching state relative to other modules. (See attached...) Figure 7 As shown, due to the identity of the average switching function, the average voltage of the capacitor always remains in a balanced state, which meets the core requirement of voltage equalization in the ISOP architecture input series and ensures stable system operation.

[0090] Step 5: Output Ripple Suppression

[0091] By using a time-sharing, staggered operation mode for each module, the centralized power output is distributed across different time periods, smoothing the charging and discharging process of the output filter capacitor and reducing system output voltage ripple.

[0092] In the existing synchronous burst mode control scheme, all modules are synchronously turned on and off, and the system output voltage can be expressed as:

[0093]

[0094] in, For the system output current, For system output filter capacitor, This refers to the module resonant current. Unlike the synchronous mode where all modules operate synchronously and are powered within the same time interval, this embodiment adopts an interleaved operation mode, where the power supply time of each module is distributed across different time periods. Therefore, compared to the synchronous burst mode, interleaved operation significantly reduces output voltage ripple, making the output voltage ripple more stable. This indicates that relaxing the instantaneous power equalization constraint and allowing phase-shifted operation can effectively improve the overall output performance of the ISOP system.

[0095] The actual test results of this embodiment are in high agreement with the theoretical analysis. Through interleaved burst mode control, the amplitude of the system output voltage ripple is significantly reduced compared with the synchronous burst mode. That is, if there are N modules, it is reduced to 1 / N. At the same time, the system efficiency under light load conditions is basically the same as that under the synchronous burst mode, realizing the synergistic optimization of light load efficiency improvement and output ripple suppression, while ensuring the input voltage balance and stable operation of the ISOP system.

[0096] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for interleaved burst mode operation control of a low-ripple ISOP resonant converter, characterized in that, The ISOP resonant converter system includes N identical LLC resonant converter modules, where N is a positive integer greater than or equal to 2. The input sides of all the LLC resonant converter modules are connected in series to form the system's high-voltage DC input terminal, and the output sides of all the LLC resonant converter modules are connected in parallel to form the system's low-voltage DC output terminal. Each LLC resonant converter module adopts a half-bridge LLC resonant topology, including a half-bridge power switching unit, a resonant cavity composed of a resonant inductor and a resonant capacitor connected in series, a transformer with a magnetizing inductor, a rectifier unit, and an output filter capacitor. The control method includes the following steps: S1. Real-time acquisition of the output load power of the ISOP resonant converter system. Determine the output load power Is the power level below the preset light load power threshold? If yes, activate the interleaved burst mode control; if no, control all LLC resonant converter modules to operate in continuous resonant mode. S2. Based on the currently collected output load power Output power corresponding to the system's preset peak efficiency power point The burst mode core control parameters of each LLC resonant converter module are calculated and configured, and the burst conduction phase offset of each module is configured according to the number of modules N; the core control parameters include the burst conduction duration. Duration of sudden shutdown Sudden cycle, sudden duty cycle With burst frequency ; S3. Control each LLC resonant converter module to perform burst conduction operation in a time-division manner according to the configured phase offset, so that a single LLC resonant converter module switches to operate independently in a very short time. During the conduction period, the switching frequency of the module is equal to the natural resonant frequency of the resonant cavity, and it operates at the peak efficiency power point. During the turn-off period, all switching devices of the half-bridge power switching unit of the module remain in the off state, and the power output is suspended. S4. Force all the LLC resonant converter modules to have the same average burst switching function, so that the average output power of each module is always consistent, and ensure the average voltage balance of the input capacitors of each module, so as to meet the input voltage equalization requirement of ISOP architecture. S5. By using the time-sharing and staggered operation mode of each module, the centralized power output is distributed to different time periods, smoothing the charging and discharging process of the output filter capacitor and reducing the system output voltage ripple.

2. The method for interleaved burst mode operation control of a low-ripple ISOP resonant converter according to claim 1, characterized in that, In step S1, the light load power threshold is 10% to 20% of the rated output power of the ISOP resonant converter system.

3. The method for interleaved burst mode operation control of a low-ripple ISOP resonant converter according to claim 1, characterized in that, In step S2, the burst cycle is the burst conduction duration. Duration of sudden shutdown The sum is expressed as: in, For sudden duty cycles, For burst frequencies, This is expressed as the output load power.

4. The method for interleaved burst mode operation control of a low-ripple ISOP resonant converter according to claim 1, characterized in that, In step S2, the burst conduction phase offset of each module is 360° / N, so that the burst conduction periods of N modules are evenly staggered within a burst cycle.

5. The method for interleaved burst mode operation control of a low-ripple ISOP resonant converter according to claim 1, characterized in that, In step S3, the conduction timing of the three-pulse resonant conduction operation is divided into three consecutive sub-intervals, which are, in order, the initial excitation sub-interval. First active output sub-interval Second active output sub-interval The duration of the three sub-intervals is expressed as follows: in, This represents the inherent resonant frequency of the resonant cavity.

6. The method for interleaved burst mode operation control of a low-ripple ISOP resonant converter according to claim 1, characterized in that, In step S4, the average burst switching function is the module burst switching function S within a burst cycle. b The average value; the burst switching function S b The function representing the on or off state of the module is S when the module is on. b =1, S is turned off b =0; the average burst switching function of all modules is exactly the same, expressed as: in, ~ This is the average burst switching function for the 1st to Nth LLC resonant converter modules.

7. The method for interleaved burst mode operation control of a low-ripple ISOP resonant converter according to claim 6, characterized in that, In step S4, the average output power of all modules remains consistent, satisfying the current distribution condition of the ISOP system. The current distribution condition is expressed as follows: in, ~ The average resonant current of the first to Nth LLC resonant converter modules is denoted by 〈・〉, which represents the average value within a burst cycle.

8. The method for interleaved burst mode operation control of a low-ripple ISOP resonant converter according to claim 1, characterized in that, In step S4, the input-side capacitor voltage of a single module is expressed as: in, For the module input side capacitor, Input current to the system, This represents the average value of the module's resonant current.

9. The method for interleaved burst mode operation control of a low-ripple ISOP resonant converter according to claim 1, characterized in that, In step S5, the system output voltage is expressed as: in, For the system output current, For system output filter capacitor, This refers to the resonant current flow of the module.

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