A clllc resonant converter wide operating range high efficiency control method and device based on frequency and phase shift coupling control

Abstract

This disclosure relates to a high-efficiency control method and apparatus for a CLLLC resonant converter with a wide operating range based on frequency and phase shift coupling control. The method includes: establishing an equivalent model of the CLLLC resonant converter and determining the boundary conditions that the converter must satisfy at different operating frequencies based on the constraints of the primary-side ZVS and secondary-side ZCS; performing offline parameter scanning on the operating frequency and phase shift angle under preset load conditions to determine multiple frequency-phase shift operating point pairs that optimize the converter efficiency; performing interpolation processing to construct a unified operation matrix that encapsulates the coupling relationship between frequency and phase shift; generating a control index based on the system's output requirements, querying the unified operation matrix to obtain the target switching frequency and target phase shift angle; and generating a corresponding PWM control signal to drive the CLLLC resonant converter. This disclosure achieves high efficiency and simplified control through a frequency and phase shift coupling control method, while ensuring the primary-side ZVS and secondary-side ZCS across the entire operating range.

Description

Technical Field

[0001] This disclosure relates to the field of CLLLC resonant converter control, and more specifically, to a method and apparatus for efficient control of a CLLLC resonant converter over a wide operating range based on frequency and phase shift coupling control. Background Technology

[0002] With the rapid global adoption of electric vehicles (EVs), charging infrastructure faces an urgent need for high efficiency, high stability, and integration with renewable energy. CLLLC resonant converters, due to their efficient bidirectional power transfer and symmetrical design, are widely used in EV charging and energy storage systems. However, the wide voltage range of batteries poses a significant challenge to maintaining high efficiency. Existing control methods typically employ frequency modulation (PFM) or phase shift modulation (PSM) to accommodate the wide operating range, but these methods have limitations: high-frequency switching leads to high turn-off current and demanding hardware requirements, while phase shift control may cause the primary-side switch to lose zero-voltage switching (ZVS) capability, necessitating complex frequency and phase shift coordinated control strategies, which are difficult to implement.

[0003] The closest existing techniques include a segmented frequency and phase-shift hybrid control method, which uses the resonant frequency as a dividing point: frequency modulation is used below the resonant frequency, and phase-shift control is used above the resonant frequency. Another existing technique is frequency-phase-shift hybrid control (PS-PFM), which approximates the frequency and phase-shift relationship through linear fitting, but cannot reach the optimal operating point. These methods are based on a typical CLLLC converter topology, including the primary-side switching bridge (Q1-Q4), resonant network (Lr1, Cr1), transformer (T1), and secondary-side resonant elements (Lr2, Cr2). In terms of control, power is controlled by adjusting the switching frequency or phase shift angle, but the lack of a unified coupling mechanism leads to control redundancy and efficiency bottlenecks.

[0004] The drawbacks of existing technologies include: low efficiency: segmented control cannot maintain high peak efficiency over a wide operating range. Control complexity: real-time calculation of frequency and phase shift pairs increases the burden on the microcontroller and is difficult to implement. Soft switching loss: phase shift control may cause the primary-side switches to lose ZVS capability, increasing switching losses. Limited gain range: approximation methods (such as linear fitting) cannot reach the optimal operating point, limiting converter performance.

[0005] Therefore, one or more methods are needed to solve the above problems.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this disclosure is to provide a wide-operating-range, high-efficiency control method and apparatus for CLLLC resonant converters based on frequency and phase shift coupling control, thereby overcoming, to at least some extent, one or more problems caused by the limitations and defects of related technologies.

[0008] According to one aspect of this disclosure, a wide-operating-range, high-efficiency control method for a CLLLC resonant converter based on frequency and phase-shift coupling control is provided, comprising: An equivalent model of the CLLLC resonant converter is established, and the boundary conditions that the converter needs to satisfy at different operating frequencies are determined based on the constraints of achieving zero-voltage turn-on (ZVS) of the primary-side switch and zero-current turn-off (ZCS) of the secondary-side switch. Based on the equivalent model and boundary conditions, under preset load conditions, offline parameter scanning is performed on the operating frequency and phase shift angle to determine multiple frequency-phase shift operating point pairs that optimize converter efficiency when achieving the critical conduction mode on the secondary side. The multiple frequency-phase shift operating point pairs are interpolated, and a unified operation matrix that encapsulates the coupling relationship between frequency and phase shift is constructed. During real-time control, a control index is generated based on the system's output requirements. The unified operation matrix is ​​then directly queried through the control index to obtain the corresponding target switching frequency and target phase shift angle. Based on the target switching frequency and target phase shift angle, a corresponding PWM control signal is generated to drive the CLLLC resonant converter to work.

[0009] In one exemplary embodiment of this disclosure, the boundary conditions in the method further include: Half-cycle symmetry condition: The resonant current and resonant capacitor voltage at the end of the P mode are equal in magnitude but opposite in sign to the values ​​at the beginning of the N mode; Condition for no sudden change in voltage and current: When switching from N mode to P mode, the voltage of the resonant capacitor and the current of the resonant inductor do not change abruptly; Condition for equal average current: The half-cycle average value of the secondary resonant current is equal to the target output current.

[0010] In one exemplary embodiment of this disclosure, the offline parameter scanning in the method specifically includes: A linear traversal is performed, using the operating frequency as the outer scan variable. For each current frequency, the phase shift angle is used as the inner variable, and a fast search is performed using the bisection method until the optimal phase shift angle that satisfies the boundary conditions and makes the converter operate in the critical conduction mode of the secondary side is found.

[0011] In one exemplary embodiment of this disclosure, the method for determining the optimal phase shift angle further includes: For each current frequency and the scanned phase shift angle, solve the differential equation of the equivalent model to obtain the time-domain expression of the resonant current; Calculate the average output current at the operating point and compare it with the preset target full-load current value. When the difference between the two is less than the preset threshold, the phase shift angle is determined to be the optimal phase shift angle.

[0012] In one exemplary embodiment of this disclosure, the method further includes: The preset threshold is 10. -8 .

[0013] In one exemplary embodiment of this disclosure, the unified operation matrix in the method is a monotonically increasing two-dimensional array stored in the memory of the microcontroller for direct addressing via index during real-time control.

[0014] In one exemplary embodiment of this disclosure, the control index in the method is generated in real time by the system's PI controller based on the feedback error of the output voltage or current.

[0015] In one exemplary embodiment of this disclosure, the offline parameter scanning in the method is performed under full load conditions.

[0016] In one exemplary embodiment of this disclosure, the method for implementing secondary-side ZCS is as follows: in the over-resonant operating region, phase shift control is added on the basis of frequency conversion control to force the converter into the operating mode O mode where the input voltage of the resonant network is zero, so that the secondary-side resonant current drops to zero before the end of half-cycle.

[0017] In one aspect of this disclosure, a wide-operating-range, high-efficiency control device for a CLLLC resonant converter based on frequency and phase-shift coupling control is provided, comprising: The modeling and solving module is used to establish the equivalent model of the CLLLC resonant converter and determine the boundary conditions that the converter needs to satisfy at different operating frequencies based on the constraints of achieving zero voltage turn-on (ZVS) of the primary-side switch and zero current turn-off (ZCS) of the secondary-side switch. The offline parameter scanning module is used to perform offline parameter scanning on the operating frequency and phase shift angle under preset load conditions based on the equivalent model and boundary conditions, so as to determine multiple frequency-phase shift operating point pairs that optimize the converter efficiency when realizing the critical conduction mode of the secondary side. The matrix construction module is used to interpolate the multiple frequency-phase shift operating point pairs and construct a unified operation matrix that encapsulates the coupling relationship between frequency and phase shift. The index query module is used to generate a control index based on the system's output requirements during real-time control. The unified operation matrix is ​​then directly queried through the control index to obtain the corresponding target switching frequency and target phase shift angle. The PWM signal generation module is used to generate a corresponding PWM control signal based on the target switching frequency and the target phase shift angle to drive the CLLLC resonant converter to work.

[0018] An exemplary embodiment of this disclosure discloses a wide-operating-range high-efficiency control method for a CLLLC resonant converter based on frequency and phase shift coupling control. The method includes: establishing an equivalent model of the CLLLC resonant converter and determining the boundary conditions that the converter needs to satisfy at different operating frequencies based on the constraints of achieving zero-voltage turn-on (ZVS) for the primary-side switch and zero-current turn-off (ZCS) for the secondary-side switch; based on the equivalent model and boundary conditions, performing offline parameter scanning of the operating frequency and phase shift angle under preset load conditions to determine multiple frequency-phase shift operating point pairs that optimize converter efficiency when achieving the critical conduction mode on the secondary side; interpolating the multiple frequency-phase shift operating point pairs and constructing a unified operation matrix that encapsulates the coupling relationship between frequency and phase shift; during real-time control, generating a control index based on the system's output requirements, directly querying the unified operation matrix through the control index to obtain the corresponding target switching frequency and target phase shift angle; and generating a corresponding PWM control signal based on the target switching frequency and target phase shift angle to drive the CLLLC resonant converter. This disclosure achieves high efficiency and simplified control through frequency and phase shift coupling control methods, and ensures primary-side ZVS and secondary-side zero-current switching throughout the entire operating range.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0020] The above and other features and advantages of this disclosure will become more apparent from the detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0021] Figure 1 A flowchart is shown below illustrating an exemplary embodiment of the present disclosure of a wide-operating-range efficient control method for a CLLLC resonant converter based on frequency and phase shift coupling control. Figure 2 An equivalent circuit diagram of a CLLLC resonant converter is shown, illustrating an efficient control method for a wide operating range CLLLC resonant converter based on frequency and phase shift coupling control according to an exemplary embodiment of the present disclosure. Figures 3A-3CThe diagram shows the CLLLC operating mode equivalent circuit of a CLLLC resonant converter with a wide operating range and an efficient control method based on frequency and phase shift coupling control according to an exemplary embodiment of the present disclosure. Figure 4 A schematic diagram of the CLLLC offline scanning path is shown in an exemplary embodiment of the present disclosure, illustrating a CLLLC resonant converter with a wide operating range and high efficiency control method based on frequency and phase shift coupling control. Figure 5 A system control block diagram is shown for an efficient control method for a CLLLC resonant converter with a wide operating range based on frequency and phase shift coupling control, according to an exemplary embodiment of the present disclosure. Figure 6 A schematic block diagram of a wide-operating-range, high-efficiency control device for a CLLLC resonant converter based on frequency and phase-shift coupling control is shown according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0022] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0023] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of the specific details described, or other methods, components, materials, apparatuses, steps, etc., can be employed. In other instances, well-known structures, methods, apparatuses, implementations, materials, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0024] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, or in one or more software-hardened modules, or in different network and / or processor devices and / or microcontroller devices.

[0025] In this example embodiment, a high-efficiency control method for a CLLLC resonant converter with a wide operating range based on frequency and phase shift coupling control is first provided; Reference Figure 1As shown, the efficient control method for a CLLLC resonant converter with a wide operating range based on frequency and phase shift coupling control may include the following steps: Step S110: Establish the equivalent model of the CLLLC resonant converter, and determine the boundary conditions that the converter needs to satisfy at different operating frequencies based on the constraints of achieving zero voltage turn-on (ZVS) of the primary-side switch and zero current turn-off (ZCS) of the secondary-side switch. Step S120: Based on the equivalent model and boundary conditions, under preset load conditions, perform offline parameter scanning on the operating frequency and phase shift angle to determine multiple frequency-phase shift operating point pairs that optimize converter efficiency when achieving the critical conduction mode on the secondary side. Step S130: Interpolate the multiple frequency-phase shift operating point pairs and construct a unified operation matrix that encapsulates the coupling relationship between frequency and phase shift; Step S140: During real-time control, a control index is generated according to the system's output requirements. The unified operation matrix is ​​directly queried through the control index to obtain the corresponding target switching frequency and target phase shift angle. Step S150: Generate a corresponding PWM control signal based on the target switching frequency and the target phase shift angle to drive the CLLLC resonant converter to work.

[0026] An exemplary embodiment of this disclosure discloses a wide-operating-range high-efficiency control method for a CLLLC resonant converter based on frequency and phase shift coupling control. The method includes: establishing an equivalent model of the CLLLC resonant converter and determining the boundary conditions that the converter needs to satisfy at different operating frequencies based on the constraints of achieving zero-voltage turn-on (ZVS) for the primary-side switch and zero-current turn-off (ZCS) for the secondary-side switch; based on the equivalent model and boundary conditions, performing offline parameter scanning of the operating frequency and phase shift angle under preset load conditions to determine multiple frequency-phase shift operating point pairs that optimize converter efficiency when achieving the critical conduction mode on the secondary side; interpolating the multiple frequency-phase shift operating point pairs and constructing a unified operation matrix that encapsulates the coupling relationship between frequency and phase shift; during real-time control, generating a control index based on the system's output requirements, directly querying the unified operation matrix through the control index to obtain the corresponding target switching frequency and target phase shift angle; and generating a corresponding PWM control signal based on the target switching frequency and target phase shift angle to drive the CLLLC resonant converter. This disclosure achieves high efficiency and simplified control through frequency and phase shift coupling control methods, and ensures primary-side ZVS and secondary-side zero-current switching throughout the entire operating range.

[0027] The following will further explain a method for efficient control of a CLLLC resonant converter with a wide operating range based on frequency and phase shift coupling control in this example embodiment.

[0028] Example 1: In step S110, an equivalent model of the CLLLC resonant converter is established, and the boundary conditions that the converter needs to satisfy at different operating frequencies are determined based on the constraints of achieving zero-voltage turn-on (ZVS) of the primary-side switch and zero-current turn-off (ZCS) of the secondary-side switch.

[0029] In this example embodiment, the boundary conditions in the method further include: Half-cycle symmetry condition: The resonant current and resonant capacitor voltage at the end of the P mode are equal in magnitude but opposite in sign to the values ​​at the beginning of the N mode; Condition for no sudden change in voltage and current: When switching from N mode to P mode, the voltage of the resonant capacitor and the current of the resonant inductor do not change abruptly; Condition for equal average current: The half-cycle average value of the secondary resonant current is equal to the target output current.

[0030] In step S120, based on the equivalent model and boundary conditions, an offline parameter scan can be performed on the operating frequency and phase shift angle under preset load conditions to determine multiple frequency-phase shift operating point pairs that optimize converter efficiency when achieving the secondary side critical conduction mode.

[0031] In this example embodiment, the offline parameter scanning in the method specifically includes: A linear traversal is performed, using the operating frequency as the outer scan variable. For each current frequency, the phase shift angle is used as the inner variable, and a fast search is performed using the bisection method until the optimal phase shift angle that satisfies the boundary conditions and makes the converter operate in the critical conduction mode of the secondary side is found.

[0032] In this example embodiment, the method for determining the optimal phase shift angle further includes: For each current frequency and the scanned phase shift angle, solve the differential equation of the equivalent model to obtain the time-domain expression of the resonant current; Calculate the average output current at the operating point and compare it with the preset target full-load current value. When the difference between the two is less than the preset threshold, the phase shift angle is determined to be the optimal phase shift angle.

[0033] In this example embodiment, the method further includes: The preset threshold is 10. -8 .

[0034] In step S130, the multiple frequency-phase shift operating point pairs can be interpolated, and a unified operation matrix that encapsulates the coupling relationship between frequency and phase shift can be constructed.

[0035] In this example embodiment, the unified operation matrix in the method is a monotonically increasing two-dimensional array stored in the microcontroller's memory, used for direct addressing via index during real-time control.

[0036] In step S140, during real-time control, a control index can be generated based on the system's output requirements. The unified operation matrix can be directly queried through the control index to obtain the corresponding target switching frequency and target phase shift angle.

[0037] In this example embodiment, the control index in the method is generated in real time by the system's PI controller based on the feedback error of the output voltage or current.

[0038] In step S150, a corresponding PWM control signal can be generated based on the target switching frequency and the target phase shift angle to drive the CLLLC resonant converter to work.

[0039] In this example embodiment, the offline parameter scanning in the method is performed under full load conditions.

[0040] In the embodiment of this example, the method to achieve secondary-side ZCS is as follows: in the over-resonant operating region, phase shift control is added on the basis of frequency conversion control to force the converter into the operating mode O mode where the input voltage of the resonant network is zero, so that the secondary-side resonant current drops to zero before the end of half-cycle.

[0041] Example 2: This invention aims to solve the problems of low efficiency, complex control, and soft-switching loss in existing CLLLC resonant converters over a wide operating range. By providing a frequency and phase shift coupled control method, high efficiency and simplified control implementation are achieved, while ensuring primary-side zero-current switching (ZVS) and secondary-side zero-current switching (ZCS) throughout the entire operating range.

[0042] In this example embodiment, the present invention proposes a frequency and phase shift coupling control strategy, the core of which is to find the frequency and phase shift pair that makes the primary side ZVS and secondary side ZCS of the converter on the gain plane, and encapsulate the correlation data of frequency and phase shift into a unified operation matrix.

[0043] This solution addresses the shortcomings of existing solutions in the following ways: ① By appropriately adding phase shift control on the basis of frequency conversion control in the over-resonance operating region, the converter is forced to enter the working state where the input voltage of the resonant network is 0, so that the resonant current on the secondary side will be 0A before the end of half-cycle, reducing the reverse recovery current, improving efficiency, and solving the shortcomings of low efficiency in the existing technology. ② The amount of phase shift to be increased is determined based on the resonant current of the secondary side. After fixing the frequency, the phase shift is gradually increased until the secondary side current is discontinuous when fully loaded. At this time, the current of the secondary side switch is reduced to zero before it is turned off, thus achieving zero current turn-off of the secondary side. ③ This invention, through refined frequency phase shift search, can find the optimal operating frequency phase shift pair to the maximum extent, rather than the coarse fitting of the two endpoints of the existing method, so that the converter can operate stably at the optimal frequency phase shift across the entire range. ④ After finding the optimal working trajectory, this invention abstracts the result into a matrix and stores it as a two-dimensional array in the microcontroller. In use, the loop output can directly index this array to obtain the corresponding frequency and phase shift, placing almost no additional burden on the controller.

[0044] In this example embodiment, the technical solution of the present invention includes the following steps: Topology and Modeling: Based on Figure 2 The equivalent circuit of the CLLLC converter is described by establishing differential equations using Kirchhoff's laws (e.g., equation (1.1)). The operating modes of the converter are divided into P-mode (energy flows from the primary side to the secondary side), N-mode (energy flows from the secondary side to the primary side), and O-mode (no energy transfer), as shown in equation (1.1). Figures 3A-3C As shown.

[0045] (1.1) From (1.1), the expressions for the resonant capacitor voltage and the resonant inductor current can be obtained as shown in (1.2): (1.2) The simplified version is shown in (1.3): (1.3) To achieve ZCS on the secondary side of the converter, it needs to be in O mode at the end of the half-cycle. Under full load, its operating mode is NP mode, therefore a phase shift is needed to change the operating mode to NPO mode. The boundary condition from NP to NPO mode is the NP mode. By solving for the NP mode and substituting the phase shift, the secondary current can be made zero at the end of the P mode, thus determining the phase shift corresponding to satisfying the condition at the current frequency. To achieve NP mode output, the following three conditions must be met simultaneously: ① Half-cycle symmetry: That is, the voltage and current values ​​at the end of P are different from the voltage and current values ​​at the beginning of N by one sign; ② Voltage and current do not change abruptly: When switching from N to P, the capacitor voltage and inductor current do not change abruptly due to their physical characteristics; ③ Equal average current: The half-cycle average value of the secondary resonant current should be equal to the target output current.

[0046] Based on the first three conditions mentioned above, we can obtain a series of equations as shown in (1.4): (1.4) To facilitate the solution by mathematical software, equation (1.3) under multiple modes can be combined and the following matrix equation can be obtained based on all the equations except for the equality of average current: (1.5) in, , , , , , , and .

[0047] 2. Parameter Scanning and Matrix Generation: Through offline parameter scanning (using MATLAB tools), the optimal frequency and phase shift pair for achieving the critical conduction mode on the secondary side under full load are determined by traversing the gain surface. The entire scanning process is divided into two layers: the outermost layer is a frequency scan, which is a linear traversal; the inner layer is a phase shift scan, which uses a bisection method to quickly locate the phase shift that meets the conditions. After finding the phase shift, the inner layer scan is exited, and the process continues to the next frequency. The scanning process is as follows: Figure 4 As shown, an operation trajectory is formed to ensure ZCS.

[0048] During each scan, the following calculations are performed: First, equation (1.5) is expressed as AX=b. The X coefficient vector is solved using Matlab to obtain the result Xsolved. Xsolved is then substituted into equation (1.3) corresponding to each mode. Substituting these values ​​into equation (1.3) for NP, the voltage and current expressions for the N and P stages are obtained. At this point, for… The average value of the phase expression is calculated to obtain the average output current of the entire cycle. The difference between this average value and the current under full load is calculated. When the difference is small enough (the threshold is 10 to the power of -8), the two values ​​are considered equal, that is, the optimal phase shift at the current frequency has been found.

[0049] 3. Establish a mapping matrix: Encode discrete frequency phase shift pairs into a monotonically increasing operation matrix and store it in the microcontroller's memory. The matrix abstracts the coupling relationship between the two quantities, simplifying real-time control.

[0050] 4. Real-time control implementation: such as Figure 5 As shown, the system outputs index values ​​through a PI controller, and the index operation matrix directly obtains the switching period and phase shift to generate a PWM signal. This method avoids complex online calculations and is suitable for DSP or MCU platforms.

[0051] In this example embodiment, the beneficial effects of the technical solution of the present invention are as follows: ① High efficiency: By limiting the phase shift correlation of the operating frequency through the working matrix, the converter can operate on the agreed optimal operating trajectory over a wide range of operating conditions, increasing the converter's operating efficiency. On the experimental prototype, the peak efficiency reached 97.14% over a wide operating range, which is superior to existing strategies.

[0052] ②Simplified control: By using a pre-calculated working matrix, the computational burden of the optimal working path is placed in the offline calculation part. Therefore, when running in the microcontroller, indexing the working frequency and phase shift from the array requires almost no additional time, reducing the complexity of the microcontroller.

[0053] ③ Soft switching retention: During offline calculation, by solving equations under specific operating mode combinations that satisfy ZVS and ZCS, the primary side ZVS and secondary side ZCS are ensured, reducing switching losses and EMI.

[0054] ④ Wide-range operation: Because phase shift control is added to the frequency conversion, a larger gain range can be obtained within the same frequency range. Through frequency and phase shift coupling, a wider gain range under narrower frequency variations is achieved.

[0055] It should be noted that although the steps of the method in this disclosure are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or a step may be broken down into multiple steps.

[0056] Furthermore, this example embodiment also provides a high-efficiency control device for a CLLLC resonant converter with a wide operating range based on frequency and phase shift coupling control. (Refer to...) Figure 6 As shown, the wide-operating-range high-efficiency control device 200 for a CLLLC resonant converter based on frequency and phase shift coupling control may include: a modeling and solving module 210, an offline parameter scanning module 220, a matrix construction module 230, an index query module 240, and a PWM signal generation module 250. Wherein: The modeling and solving module 210 is used to establish the equivalent model of the CLLLC resonant converter and, based on the constraints of achieving zero-voltage turn-on (ZVS) of the primary-side switch and zero-current turn-off (ZCS) of the secondary-side switch, determine the boundary conditions that the converter needs to satisfy at different operating frequencies. The offline parameter scanning module 220 is used to perform offline parameter scanning on the operating frequency and phase shift angle under preset load conditions based on the equivalent model and boundary conditions, so as to determine multiple frequency-phase shift operating point pairs that optimize the converter efficiency when realizing the secondary side critical conduction mode. The matrix construction module 230 is used to interpolate the multiple frequency-phase shift operating point pairs and construct a unified operation matrix that encapsulates the coupling relationship between frequency and phase shift. The index query module 240 is used to generate a control index according to the output requirements of the system during real-time control, and to directly query the unified operation matrix through the control index to obtain the corresponding target switching frequency and target phase shift angle. The PWM signal generation module 250 is used to generate a corresponding PWM control signal based on the target switching frequency and the target phase shift angle to drive the CLLLC resonant converter to work.

[0057] The specific details of each of the above-mentioned CLLLC resonant converter wide operating range high-efficiency control device modules based on frequency and phase shift coupling control have been described in detail in the corresponding CLLLC resonant converter wide operating range high-efficiency control method based on frequency and phase shift coupling control, so they will not be repeated here.

[0058] It should be noted that although several modules or units of a high-efficiency control device 200 for a CLLLC resonant converter with a wide operating range based on frequency and phase shift coupling control have been mentioned in the detailed description above, this division is not mandatory. In fact, according to embodiments of this disclosure, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0059] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of the present invention, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0060] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0061] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A wide operating range high efficiency control method for CLLLc resonant converter based on frequency and phase-shift coupling control, characterized in that, The method includes: An equivalent model of the CLLLC resonant converter is established, and the boundary conditions that the converter needs to satisfy at different operating frequencies are determined based on the constraints of achieving zero-voltage turn-on (ZVS) of the primary-side switch and zero-current turn-off (ZCS) of the secondary-side switch. Based on the equivalent model and boundary conditions, under preset load conditions, offline parameter scanning is performed on the operating frequency and phase shift angle to determine multiple frequency-phase shift operating point pairs that optimize converter efficiency when achieving the critical conduction mode on the secondary side. The multiple frequency-phase shift operating point pairs are interpolated, and a unified operation matrix that encapsulates the coupling relationship between frequency and phase shift is constructed. During real-time control, a control index is generated based on the system's output requirements. The unified operation matrix is ​​then directly queried through the control index to obtain the corresponding target switching frequency and target phase shift angle. Based on the target switching frequency and target phase shift angle, a corresponding PWM control signal is generated to drive the CLLLC resonant converter to work.

2. The method of claim 1, wherein, The boundary conditions in the method also include: Half-cycle symmetry condition: The resonant current and resonant capacitor voltage at the end of the P mode are equal in magnitude but opposite in sign to the values ​​at the beginning of the N mode; Condition for no sudden change in voltage and current: When switching from N mode to P mode, the voltage of the resonant capacitor and the current of the resonant inductor do not change abruptly; Condition for equal average current: The half-cycle average value of the secondary resonant current is equal to the target output current.

3. The method of claim 2, wherein, The offline parameter scanning in the method specifically includes: A linear traversal is performed, using the operating frequency as the outer scan variable. For each current frequency, the phase shift angle is used as the inner variable, and a fast search is performed using the bisection method until the optimal phase shift angle that satisfies the boundary conditions and makes the converter operate in the critical conduction mode of the secondary side is found.

4. The method of claim 2, wherein, The method for determining the optimal phase shift angle further includes: For each current frequency and the scanned phase shift angle, solve the differential equation of the equivalent model to obtain the time-domain expression of the resonant current; Calculate the average output current at the operating point and compare it with the preset target full-load current value. When the difference between the two is less than the preset threshold, the phase shift angle is determined to be the optimal phase shift angle.

5. The method of claim 4, wherein, The method further includes: The preset threshold is 10 -8 .

6. The method of claim 3, wherein, The unified operation matrix in the method is a monotonically increasing two-dimensional array stored in the microcontroller's memory, used for direct addressing via index during real-time control.

7. The method of claim 4, wherein, The control index in the method is generated in real time by the system's PI controller based on the feedback error of the output voltage or current.

8. The method of claim 2, wherein, The offline parameter scanning in the method is performed under full load conditions.

9. The method of claim 1, wherein, The method described above achieves secondary-side ZCS by adding phase-shift control to the frequency conversion control in the over-resonant operating region, forcing the converter into the O-mode operating mode where the input voltage of the resonant network is zero, so that the secondary-side resonant current drops to zero before the end of the half-cycle.

10. A wide operation range high efficiency control device for CLLLc resonant converter based on frequency and phase-shift coupling control, characterized in that, The device includes: The modeling and solving module is used to establish the equivalent model of the CLLLC resonant converter and determine the boundary conditions that the converter needs to satisfy at different operating frequencies based on the constraints of achieving zero voltage turn-on (ZVS) of the primary-side switch and zero current turn-off (ZCS) of the secondary-side switch. The offline parameter scanning module is used to perform offline parameter scanning on the operating frequency and phase shift angle under preset load conditions based on the equivalent model and boundary conditions, so as to determine multiple frequency-phase shift operating point pairs that optimize the converter efficiency when realizing the critical conduction mode of the secondary side. The matrix construction module is used to interpolate the multiple frequency-phase shift operating point pairs and construct a unified operation matrix that encapsulates the coupling relationship between frequency and phase shift. The index query module is used to generate a control index based on the system's output requirements during real-time control. The unified operation matrix is ​​then directly queried through the control index to obtain the corresponding target switching frequency and target phase shift angle. The PWM signal generation module is used to generate a corresponding PWM control signal based on the target switching frequency and the target phase shift angle to drive the CLLLC resonant converter to work.

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