Particle swarm optimization method for resonant parameters of bidirectional LLC converter

Abstract

The present application relates to the technical field of converter parameter optimization, and in particular to a particle swarm optimization method and system for resonant parameters of a bidirectional LLC converter, including establishing a loss model for an LLC full-bridge converter, calculating the total power loss under the premise of introducing inductance ratio and quality factor; using the inductance ratio and quality factor as replacement variables for the resonant inductance, excitation inductance, and resonant capacitance; calculating the gain of the LLC full-bridge converter and solving to obtain the value range of the inductance ratio that meets the gain requirements and the value range of the quality factor that meets the soft switching conditions; continuously updating the inductance ratio and quality factor through a particle swarm optimization algorithm, and determining the resonant inductance, excitation inductance, and resonant capacitance corresponding to the inductance ratio and quality factor as the optimal parameters. The present application can realize the design of complex resonant parameters in the LLC full-bridge converter under the premise of meeting the user-side energy storage system's requirements for bidirectional energy flow and high-efficiency conversion.

Description

Technical Field

[0001] The present application relates to the technical field of converter parameter optimization, and in particular to a particle swarm optimization method for resonant parameters of a bidirectional LLC converter. Background Art

[0002] In recent years, to meet the stringent safety, efficiency, and reliability requirements of user-side energy storage systems, the DC-DC converters used must not only achieve stable voltage conversion, but also withstand moderate current and voltage stresses while maintaining high energy transmission efficiency. The LLC resonant converter, a high-efficiency conversion technology that enables soft switching and reduces losses, is widely used in such systems. Among them, the LLC full-bridge converter, as the most common structure of LLC resonant converters, can better meet the aforementioned requirements for DC-DC converters and has therefore attracted widespread attention and application in the industry.

[0003] In existing LLC full-bridge converter designs, the operating efficiency of the LLC full-bridge converter is closely related to the parameters of the resonant cavity. The converter contains three resonant elements: the resonant inductor Lr, the excitation inductor Lm, and the resonant capacitor Cr. The interaction between these three elements is not a simple linear relationship; their coupling effects and influencing mechanisms are relatively complex, making parameter optimization a long-standing challenge in hardware design. Currently, there are two main parameter design methods for LLC full-bridge converters. One method quantitatively calculates the converter's operating losses by establishing a time-domain relationship between the resonant current Ir, the excitation current Im, and the dead time td. From this, the relationship between losses and dead time is derived. Combined with the formula for calculating the effective values ​​of the primary and secondary currents of the transformer, the appropriate resonant parameters are solved. The other method selects a set of parameters within a given parameter range, verifies through simulation whether the converter operates in the PO mode, and checks whether the gain meets the requirements. If not, the parameters are adjusted until all conditions are met.

[0004] However, these methods have limitations. For example, the time-domain loss model method often assumes the converter operates in a specific mode when establishing the relationship between the resonant current Ir, the excitation current Im, and the dead time td. However, in practice, the converter's operating mode may vary, causing the loss model to deviate from the actual situation and affecting the accuracy of the subsequent parameter solution. Furthermore, the parameter selection and simulation verification method requires repeated parameter adjustments within a given parameter range: first, simulation is used to verify that the converter is in the PO mode; then, the gain is verified to meet the requirements. If not, the parameters must be reselected and verified again. This process not only makes the design process lengthy and complex, but also, because existing solutions are only designed for LLC full-bridge converters with unidirectional energy flow, their parameter tuning is difficult to directly extend to bidirectional energy transmission systems. Therefore, how to design the complex resonant parameters of the LLC full-bridge converter while meeting the user-side energy storage system's requirements for bidirectional energy flow and high-efficiency conversion, thereby overcoming the limitations of unidirectional designs, remains a challenge. Summary of the Invention

[0005] This application provides a particle swarm optimization method and system for bidirectional LLC converter resonant parameters, which can achieve the design of complex resonant parameters in LLC full-bridge converters while meeting the user-side energy storage system's requirements for bidirectional energy flow and high-efficiency conversion. This application provides the following technical solutions:

[0006] In a first aspect, the present application provides a particle swarm optimization method for resonant parameters of a bidirectional LLC converter, the method comprising:

[0007] Establish an LLC full-bridge converter loss model. The LLC full-bridge converter loss model is used to calculate the total power loss of the LLC full-bridge converter in forward and reverse operation under the premise of introducing the inductance ratio and quality factor.

[0008] Through mathematical derivation of the resonant circuit, the inductance ratio and quality factor are used as replacement variables for the resonant inductance, magnetizing inductance, and resonant capacitance. The gain of the LLC full-bridge converter is calculated, and the range of inductance ratio values ​​that meet the gain requirements and the range of quality factor values ​​that meet the soft switching conditions are determined.

[0009] Based on the LLC full-bridge converter loss model and the obtained inductance ratio and quality factor ranges, the inductance ratio and quality factor are continuously updated through the particle swarm optimization algorithm until the loss of the LLC full-bridge converter is minimized and no longer changes. The resonant inductance, excitation inductance, and resonant capacitance corresponding to the inductance ratio and quality factor at this time are determined as the optimal parameters.

[0010] In a specific embodiment, establishing the LLC full-bridge converter loss model includes:

[0011] Normalization sets the switching frequency;

[0012] Inductance ratio and quality factor are introduced to calculate the key current parameters of the LLC full-bridge converter at the forward resonant frequency point. The key current parameters include the effective value of the resonant current, the maximum value of the excitation current, and the effective value of the secondary current;

[0013] The total power loss of the converter in forward and reverse operation is calculated based on the calculated key current parameters.

[0014] In a specific embodiment, the calculation of the total power loss of the converter in forward and reverse operation based on the calculated key current parameters includes:

[0015] The total power loss of the converter in forward and reverse operation is the sum of the power loss of the resonant side MOS tube in forward and reverse operation, the power loss of the non-resonant side MOS tube in forward and reverse operation, the power loss of the resonant cavity in forward and reverse operation, and the power loss of the transformer in forward and reverse operation.

[0016] In a specific implementation scheme, the step of calculating the gain of the LLC full-bridge converter and solving for a value range of the inductance ratio that meets the gain requirement and a value range of the quality factor that meets the soft switching condition includes:

[0017] Gain satisfaction: ;

[0018] and The calculation formula is as follows:

[0019] ;

[0020] in, and is the highest and lowest voltage of the battery, is the DC bus voltage, is the turns ratio of the transformer;

[0021] Under no-load conditions, the quality factor is 0, the gain formula is as follows:

[0022] .

[0023] In a specific embodiment, the step of calculating the gain of the LLC full-bridge converter and solving for a value range of the inductance ratio that meets the gain requirement and a value range of the quality factor that meets the soft switching condition further includes:

[0024] In order to ensure that the gain of the LLC full-bridge converter can meet the minimum requirement, the normalized frequency Take the maximum value ,at this time:

[0025] ;

[0026] Solve to obtain the inductance ratio that meets the gain requirements range.

[0027] In a specific embodiment, the step of calculating the gain of the LLC full-bridge converter and solving for a value range of the inductance ratio that meets the gain requirement and a value range of the quality factor that meets the soft switching condition further includes:

[0028] In order to ensure that the LLC full-bridge converter can achieve soft switching, that is, to ensure that the main switch is turned on at zero voltage, the imaginary part of the input impedance needs to be zero. The corresponding critical conditions are as follows:

[0029] ;

[0030] At full load, , and bring it into the above formula, combined with the following gain requirements:

[0031] ;

[0032] Solve to obtain the quality factor that meets the soft switching conditions The value range of .

[0033] In a specific feasible implementation scheme, based on the LLC full-bridge converter loss model and the obtained inductance ratio and quality factor value ranges, the inductance ratio and quality factor are continuously updated by a particle swarm optimization algorithm until the loss of the LLC full-bridge converter is minimized and no longer changes, and the resonant inductance, excitation inductance, and resonant capacitance corresponding to the inductance ratio and quality factor at this time are determined as optimal parameters, including:

[0034] Establish an LLC full-bridge converter simulation model on MATLAB / SIMULINK, define the design parameters of the LLC full-bridge converter and the model parameters of the LLC full-bridge converter loss model;

[0035] After defining the design parameters of the LLC full-bridge converter and the model parameters of the LLC full-bridge converter loss model, the loss model parameters are substituted into the loss model of the LLC full-bridge converter to obtain the sum of the forward working loss and the reverse working loss of the LLC full-bridge converter;

[0036] The particle swarm algorithm is used for optimization and substituted into the LLC full-bridge converter simulation model for simulation calculation. The sum of the forward working loss and reverse working loss of the LLC full-bridge converter is obtained. The algorithm is iterated continuously until the loss of the LLC full-bridge converter is minimized and no longer changes. The resonant inductance, excitation inductance, and resonant capacitance corresponding to the inductance ratio and quality factor at this time are determined and used as the optimal parameters in the LLC full-bridge converter.

[0037] In a second aspect, the present application provides a particle swarm optimization system for resonant parameters of a bidirectional LLC converter, which adopts the following technical solutions:

[0038] A particle swarm optimization system for resonant parameters of a bidirectional LLC converter, comprising:

[0039] The loss model establishment module is used to establish the LLC full-bridge converter loss model. The LLC full-bridge converter loss model is used to calculate the total power loss of the LLC full-bridge converter in forward and reverse operation under the premise of introducing the inductance ratio and quality factor.

[0040] A value range determination module is used to use the inductance ratio and quality factor as replacement variables for the resonant inductance, excitation inductance, and resonant capacitance through mathematical derivation of the resonant circuit; calculate the gain of the LLC full-bridge converter and solve for the value range of the inductance ratio that meets the gain requirements and the value range of the quality factor that meets the soft switching conditions;

[0041] The parameter update module is used to continuously update the inductance ratio and quality factor based on the LLC full-bridge converter loss model and the obtained value range of the inductance ratio and quality factor through a particle swarm optimization algorithm until the loss of the LLC full-bridge converter is minimized and no longer changes. The resonant inductance, excitation inductance, and resonant capacitance corresponding to the inductance ratio and quality factor at this time are determined as the optimal parameters.

[0042] In a third aspect, the present application provides an electronic device comprising a processor and a memory; a program is stored in the memory, and the program is loaded and executed by the processor to implement a particle swarm optimization method for resonant parameters of a bidirectional LLC converter as described in the first aspect.

[0043] In a fourth aspect, the present application provides a computer-readable storage medium, wherein a program is stored in the storage medium, and when the program is executed by a processor, it is used to implement a particle swarm optimization method for resonant parameters of a bidirectional LLC converter as described in the first aspect.

[0044] In summary, the beneficial effects of this application include at least:

[0045] (1) By constructing an accurate loss model based on resonant circuit theory, this application converts the traditional inductance and capacitance parameters into two dimensionless parameters, inductance ratio and quality factor, during the design process, thereby reducing the dimensionality of multiple complex variables in the system and making the current distribution and loss calculation of the converter in the forward and reverse working states more accurate.

[0046] (2) By replacing the original resonant inductor, excitation inductor, and resonant capacitor with inductance ratios and quality factors, not only the number of design variables is significantly reduced, but also the coupling relationship between parameters is more intuitive and easy to understand. Combined with the particle swarm optimization algorithm, designers can automatically search for the optimal solution within the predetermined parameter range without the need for tedious manual parameter adjustments and multiple simulation verifications. Through this optimization design process, engineers can quickly obtain the optimal parameter set that meets the gain, soft switching, and power loss requirements, thereby greatly reducing the difficulty of hardware design and system debugging, and shortening the product development and iteration cycle.

[0047] A loss model for an LLC full-bridge converter was established using circuit theory and resonance principles. Key current parameters at the forward resonant frequency were calculated by normalizing the switching frequency, and the inductance ratio and quality factor were introduced as characteristic variables for the resonant inductor, magnetizing inductor, and resonant capacitor. These dimensionless parameters were mathematically derived from the resonant circuit to calculate the converter's gain, further determining the range of inductance ratio and quality factor values ​​that satisfied gain and soft-switching requirements. Using a particle swarm optimization algorithm on the MATLAB / SIMULINK simulation platform, the inductance ratio and quality factor were iteratively updated until an optimal solution was found that minimized the total forward and reverse losses of the converter and remained stable. From this, the optimal resonant inductor, resonant capacitor, and magnetizing inductor were derived. This solution not only reduced the complexity of parameter solution but also achieved high-efficiency conversion under bidirectional energy flow, addressing the shortcomings of existing design methods in hardware parameter optimization.

[0048] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application and to implement it in accordance with the contents of the specification, the following is a detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 1 is a flow chart of a particle swarm optimization method for resonant parameters of a bidirectional LLC converter in an embodiment of the present application.

[0050] Figure 2 It is a flow chart of using the particle swarm algorithm to find the optimal parameter solution in an embodiment of the present application.

[0051] Figure 3 1 is a graph showing the relationship between the optimal loss and the number of iterations of the particle swarm algorithm in an embodiment of the present application.

[0052] Figure 4 This is a forward waveform diagram obtained by using the currently common design method in the embodiment of the present application to obtain three other sets of parameters, which are then substituted into the simulation and compared with the parameters obtained by the optimization calculation of the present application.

[0053] Figure 5 This is a reverse waveform diagram of the embodiment of the present application using the currently common design method to obtain three other sets of parameters, which are then substituted into the simulation and compared with the parameters obtained by the optimization calculation of the present application.

[0054] Figure 6 It is a block diagram of an electronic device for particle swarm optimization of resonant parameters of a bidirectional LLC converter in an embodiment of the present application. DETAILED DESCRIPTION

[0055] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0056] Optionally, the present application uses the bidirectional LLC converter resonant parameter particle swarm optimization method provided in each embodiment as an example for use in an electronic device, where the electronic device is a terminal or a server. The terminal can be a mobile phone, a computer, a tablet computer, etc. This embodiment does not limit the type of electronic device.

[0057] Reference Figure 1 , is a flow chart of a particle swarm optimization method for resonant parameters of a bidirectional LLC converter provided by an embodiment of the present application. The method includes at least the following steps:

[0058] Step S101: Establishing an LLC full-bridge converter loss model. The LLC full-bridge converter loss model is used to calculate the total power loss of the LLC full-bridge converter in forward and reverse operation under the premise of introducing an inductance ratio and a quality factor.

[0059] In step S101, the actual switching frequency is first normalized and set to f n =1, calculate the key current parameters of the LLC full-bridge converter at the forward resonant frequency point, including the effective value of the resonant current , maximum excitation current And the effective value of the secondary current Based on circuit theory and the working principle of resonant circuit, the inductance ratio and quality factor are introduced. After mathematical derivation, the calculation formula is as follows:

[0060] ;

[0061] in, Indicates the total power loss in the forward and reverse rated working conditions. is the turns ratio of the transformer, is the secondary voltage, is the secondary rated current, is the inductance ratio, which is used to reflect the coupling ratio between the resonant inductance and the excitation inductance. is the quality factor, which is used to measure the balance between energy storage and loss in a resonant circuit.

[0062] Then, the total power loss of the converter in forward and reverse operation is calculated based on the calculated key current parameters. Specifically, first calculate the power loss of the resonant side MOS tube when it is working in the forward and reverse directions. And the power loss of the non-resonant side MOS tube when working in forward and reverse directions .

[0063] Specifically, the power loss of the resonant side MOS tube when working in forward and reverse directions is calculated as follows:

[0064] ;

[0065] in, is the conduction loss of the MOS tube on the resonant side during forward operation, is the turn-off loss of the MOS tube on the resonant side during forward operation, is the conduction loss of the MOS tube on the resonant side when working in reverse direction, It is the turn-on loss of the MOS tube when the resonant side switch tube is turned on.

[0066] ;

[0067] ;

[0068] ;

[0069] ;

[0070] in, Indicates the effective value of the resonant current of the resonant side MOS tube in the forward working state. Indicates the equivalent resistance of the MOS tube in the on state. Indicates the DC bus voltage, represents the resonant frequency, Indicates the time required to charge the internal capacitor of the MOS tube. Represents a complete switching cycle, Indicates the energy loss caused by the conduction voltage and current on the MOS tube. Indicates the effective value of the resonant current on the resonant side under reverse working conditions. Indicates the current value of the MOS tube when working in reverse. represents the impedance in the on-state, Indicates the output capacitance of the MOS tube.

[0071] Specifically, the power loss of the non-resonant side MOS tube when working in forward and reverse directions is calculated as follows:

[0072] ;

[0073] in, is the conduction loss of the non-resonant side MOS tube during forward operation, is the turn-on loss of the non-resonant side MOS tube during forward operation, is the conduction loss of the non-resonant side MOS tube when working in reverse direction, It is the turn-off loss of the MOS tube on the non-resonant side when working in reverse.

[0074] ;

[0075] ;

[0076] ;

[0077] ;

[0078] in, Indicates the rated output power, which is the power output target of the system under rated working conditions. Indicates the voltage drop when the MOS tube is turned on, that is, the voltage loss of the device in the on state. represents the turns ratio of the transformer, Indicates the equivalent resistance when the MOS tube is turned on. Indicates the effective value of the resonant current of the non-resonant side MOS tube during forward operation. Indicates the current flowing through the non-resonant side MOS tube when working in reverse. Indicates the equivalent resistance of the MOS tube in the on state. Represents the output capacitance of the MOS tube, represents the resonant frequency, Indicates the secondary voltage.

[0079] Then calculate the power loss when the resonant cavity is working in the forward and reverse directions respectively. And the power loss of the transformer during forward and reverse operation , based on circuit theory and the working principle of the resonant circuit, the calculation formula is obtained through mathematical deduction as follows:

[0080] ;

[0081] in, and are the equivalent resistances of the resonant inductor and resonant capacitor respectively, Indicates the effective value of the resonant current on the resonant side under reverse working conditions. Indicates the effective value of the resonant current of the resonant side MOS tube in the forward working state.

[0082] ;

[0083] in, and are the equivalent resistances of the primary and secondary sides of the transformer, Indicates the effective value of the resonant current on the resonant side under reverse working conditions. Indicates the effective value of the resonant current of the resonant side MOS tube in the forward working state.

[0084] Finally, the total power loss of the converter in forward and reverse operation is The power loss of the MOS tube on the resonant side when working in forward and reverse directions , the power loss of the non-resonant side MOS tube when working in forward and reverse directions , power loss when the resonant cavity works in forward and reverse directions And the power loss of the transformer during forward and reverse operation The sum is as follows:

[0085] ;

[0086] It should be noted that in this application, it represents the total power loss in the forward and reverse rated working states. Usually used as a nominal or reference value, is the detailed total power loss calculated based on the model. In other words, As a design parameter or target indicator, it is used in the formula for normalization and as an input for calculating other current parameters. It is the total loss obtained by adding up the losses of various parts (such as the switching and conduction losses of the MOS tubes on the resonant side and the non-resonant side, the losses of the resonant cavity and the transformer). In short, is a preset or expected loss value, and It is the result calculated by the model, reflecting the summary of actual losses.

[0087] Through the above steps, based on the resonant current parameters of the LLC full-bridge converter, the calculation formulas for each loss term are derived, and finally the LLC full-bridge converter loss model is obtained. The LLC full-bridge converter loss model can be used to calculate the total power loss of the converter in forward and reverse operation and is applicable to various operating conditions.

[0088] Step S102: Through mathematical derivation of the resonant circuit, the inductance ratio and the quality factor are used as replacement variables for the resonant inductance, the excitation inductance, and the resonant capacitance; the gain of the LLC full-bridge converter is calculated and the value range of the inductance ratio that meets the gain requirement and the value range of the quality factor that meets the soft switching condition are obtained.

[0089] In step S102, gain refers to the ratio of the converter's output voltage to its input voltage. In an LLC resonant converter, gain is not fixed but varies with the switching frequency. To ensure that the converter can adjust gain and maintain its output voltage within a reasonable range, the gain must satisfy the following conditions: ;

[0090] and The calculation formula is as follows:

[0091] ;

[0092] in, and is the highest and lowest voltage of the battery, is the DC bus voltage, is the turns ratio of the transformer.

[0093] In implementation, the normalized frequency Indicates the operating frequency of the converter:

[0094] ;

[0095] in, is the actual switching frequency, is the resonant frequency.

[0096] Since the gain is affected by frequency impact, so it is necessary to calculate as well as , ensuring that the converter operates within this frequency range to meet the gain requirements. Under no-load conditions, the quality factor is is 0, the gain formula is as follows:

[0097] ;

[0098] Secondly, in the LLC resonant converter, the parameter combination of the inductor and capacitor determines the working characteristics of the converter. , excitation inductance and resonant capacitors The calculation involves multiple variables, which makes the calculation complex and the difficulty of adjusting the parameters. Therefore, through the mathematical derivation of the resonant circuit, the inductance ratio of two variables is used. and quality factor As substitute variables for the resonant inductance, magnetizing inductance, and resonant capacitance, they are as follows:

[0099] ;

[0100] in, is the equivalent load impedance of the converter.

[0101] Then, in order to ensure that the gain of the LLC full-bridge converter can meet the minimum requirement, the normalized frequency Take the maximum value ,at this time:

[0102] ;

[0103] From this solution, we can get the inductance ratio that meets the gain requirements Specifically, when the normalized frequency reaches the highest value, the LLC converter gain will drop to the lowest value. In order to ensure that even in this most unfavorable working condition, the gain will not be lower than the minimum value required by the system, the gain at the highest frequency is compared with the minimum gain allowed, and their changes with the inductance ratio are observed. The specific approach is: first determine the position with the lowest gain at the highest frequency, and then analyze the relationship between the gain and the change of the gain at this position. Increasing or decreasing trend, find the k value that makes the gain just reach the lower limit; then combine The physical constraint that must be positive can provide an upper and lower bound to clearly satisfy the gain requirement. The value range of .

[0104] Then, in order to ensure that the LLC full-bridge converter can achieve soft switching, that is, to ensure that the main switch is turned on at zero voltage, the imaginary part of the input impedance needs to be 0. The corresponding critical conditions are as follows:

[0105] ;

[0106] At full load, , and bring it into the above formula, combined with the following gain requirements:

[0107] ;

[0108] Thus, the quality factor that satisfies the soft switching condition is obtained. Specifically, when the converter is operating at the heaviest load and lowest normalized frequency, to achieve zero voltage switching, the imaginary part of the input impedance must be exactly zero, so that the main switch can be turned on at the moment the voltage drops to zero. To this end, the lowest frequency is used as the observation point to observe the quality factor. Impact on input impedance phase: Adjust from small to large The imaginary part of the input impedance undergoes a change from inductive to capacitive or vice versa. Find the values ​​that make the imaginary part cross zero. Value range, that is, the soft switching condition is met Then, at the same minimum frequency, we must ensure that the converter gain is not lower than the maximum output requirement. Based on the changing trend, we can select the ones that can achieve zero voltage switching and meet the gain lower limit. The intersection of the two is the quality factor that ultimately ensures both soft switching and gain requirements. The value range of .

[0109] Step S103: Based on the LLC full-bridge converter loss model and the obtained inductance ratio and quality factor value ranges, the inductance ratio and quality factor are continuously updated through the particle swarm optimization algorithm until the loss of the LLC full-bridge converter is minimized and no longer changes. The resonant inductance, excitation inductance, and resonant capacitance corresponding to the inductance ratio and quality factor at this time are determined as optimal parameters.

[0110] In step S103, a simulation model of an LLC full-bridge converter is first established on MATLAB / SIMULINK, and then the design parameters of the LLC full-bridge converter and the model parameters of the LLC full-bridge converter loss model are defined. The design parameters of the LLC full-bridge converter and the model parameters of the LLC full-bridge converter loss model in this application are shown in Table 1 and Table 2, respectively:

[0111]

[0112]

[0113] After defining the design parameters of the LLC full-bridge converter and the model parameters of the LLC full-bridge converter loss model, the loss model parameters are substituted into the loss model of the LLC full-bridge converter to obtain the sum of the forward working loss and the reverse working loss of the LLC full-bridge converter, as shown below:

[0114] ;

[0115] Finally, the particle swarm algorithm is used for optimization. The parameter settings of the algorithm are shown in Table 3. Figure 2, define the number of iterations t, the number of particle populations N and the learning factors c1, c2, and randomly set the initial position x of each particle i and initial velocity v i , calculate the fitness of each particle, substitute it into the LLC full-bridge converter simulation model for simulation calculation, and obtain the sum of the forward working loss and reverse working loss of the LLC full-bridge converter. Then start to iterate and update the particle position continuously, calculate the new fitness, compare the individual optimal solution of each particle with the group optimal solution, and judge whether it needs to be updated until the loss of the LLC full-bridge converter is minimized and no longer changes. Determine the resonant inductance, excitation inductance and resonant capacitance corresponding to the inductance ratio and quality factor at this time as the optimal parameters in the LLC full-bridge converter.

[0116]

[0117] In this application, after 50 iterations, the relationship curve between total loss and number of iterations is shown in the attached figure. Figure 3 As shown in the figure, the total loss of the parameter group found by the particle swarm algorithm decreases with increasing iteration number, indicating that the algorithm continuously updates the optimal LLC parameters in multiple iterations. When the iteration number reaches 35, the total loss no longer changes, indicating that the algorithm has found the optimal solution. The corresponding total losses in forward and reverse operation are 382W and 498W, the inductance ratio k is 0.3, and the quality factor Q is 0.63. The calculated resonant inductance Lr is 86.7μH, the resonant capacitance Cr is 81.1nF, and the excitation inductance Lm is 289μH.

[0118] In order to verify the optimality of the particle swarm algorithm optimization results, the current common design method is used to obtain three other sets of parameters, which are substituted into the simulation and compared with the parameters obtained by the optimization calculation of the present invention. Parameter 1 resonant inductance Lr is 71.6μH, resonant capacitance Cr is 98.3nF, and excitation inductance Lm is 194μH. Parameter 2 resonant inductance Lr is 60.5μH, resonant capacitance Cr is 116nF, and excitation inductance Lm is 209μH. Parameter 3 resonant inductance Lr is 67.4μH, resonant capacitance Cr is 104nF, and excitation inductance Lm is 193μH. Substitute into the forward and reverse simulations and record the output voltage in steady state. V o , resonant current i r , excitation current i m , primary and secondary side switch voltage u g and current i g The waveform of the forward and reverse simulation waveforms are shown in the attached Figure 4 Attachment Figure 5 The simulation data corresponding to the four groups of resonance parameters are shown in Table 4.

[0119]

[0120] In summary, this application uses circuit theory and resonance principle to establish a loss model for the LLC full-bridge converter. The key current parameters at the forward resonant frequency point are calculated by normalizing the switching frequency, and the inductance ratio and quality factor are introduced as characteristic variables of the resonant inductor, excitation inductor, and resonant capacitor. Through mathematical derivation of the resonant circuit, these dimensionless parameters are used to calculate the gain of the converter, and the range of values ​​of the inductance ratio and quality factor that meet the gain and soft switching conditions is further solved. The inductance ratio and quality factor are iteratively updated using the particle swarm optimization algorithm on the MATLAB / SIMULINK simulation platform until the optimal solution that minimizes the total forward and reverse losses of the converter and remains stable is found, and the optimal resonant inductor, resonant capacitor, and excitation inductor are obtained by reverse deduction. This solution not only reduces the complexity of parameter solution, but also achieves high-efficiency conversion under bidirectional energy flow, solving the shortcomings of existing design methods in hardware parameter optimization.

[0121] An embodiment of the present application further provides a particle swarm optimization system for resonant parameters of a bidirectional LLC converter, the system comprising at least the following modules:

[0122] The loss model establishment module is used to establish the LLC full-bridge converter loss model. The LLC full-bridge converter loss model is used to calculate the total power loss of the LLC full-bridge converter in forward and reverse operation under the premise of introducing the inductance ratio and quality factor.

[0123] A value range determination module is used to use the inductance ratio and quality factor as replacement variables for the resonant inductance, excitation inductance, and resonant capacitance through mathematical derivation of the resonant circuit; calculate the gain of the LLC full-bridge converter and solve for the value range of the inductance ratio that meets the gain requirements and the value range of the quality factor that meets the soft switching conditions;

[0124] The parameter update module is used to continuously update the inductance ratio and quality factor based on the LLC full-bridge converter loss model and the obtained value range of the inductance ratio and quality factor through a particle swarm optimization algorithm until the loss of the LLC full-bridge converter is minimized and no longer changes. The resonant inductance, excitation inductance, and resonant capacitance corresponding to the inductance ratio and quality factor at this time are determined as the optimal parameters.

[0125] For relevant details, please refer to the above method embodiment.

[0126] Figure 6 4 is a block diagram of an electronic device provided in one embodiment of the present application. The device includes at least a processor 401 and a memory 402.

[0127] Processor 401 may include one or more processing cores, such as a quad-core processor or an octa-core processor. Processor 401 may be implemented in hardware using at least one of the following: a DSP (Digital Signal Processing), an FPGA (Field-Programmable Gate Array), or a PLA (Programmable Logic Array). Processor 401 may also include a main processor and a coprocessor. The main processor is used to process data in the awake state, also known as a CPU (Central Processing Unit); the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, processor 401 may be integrated with a GPU (Graphics Processing Unit), which is responsible for rendering and drawing content displayed on the display screen. In some embodiments, processor 401 may also include an AI (Artificial Intelligence) processor, which is used to handle computational operations related to machine learning.

[0128] The memory 402 may include one or more computer-readable storage media, which may be non-transitory. The memory 402 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices and flash memory storage devices. In some embodiments, the non-transitory computer-readable storage medium in the memory 402 is used to store at least one instruction, which is used to be executed by the processor 401 to implement the particle swarm optimization method for the resonant parameters of the bidirectional LLC converter provided in the method embodiment of the present application.

[0129] In some embodiments, the electronic device may optionally include a peripheral device interface and at least one peripheral device. The processor 401, memory 402, and peripheral device interface may be connected via a bus or signal lines. Each peripheral device may be connected to the peripheral device interface via a bus, signal lines, or circuit boards. Illustratively, the peripheral devices include, but are not limited to, radio frequency circuitry, a touchscreen display, audio circuitry, and a power supply.

[0130] Of course, the electronic device may also include fewer or more components, which is not limited in this embodiment.

[0131] Optionally, the present application also provides a computer-readable storage medium, in which a program is stored. The program is loaded and executed by a processor to implement the particle swarm optimization method for the resonant parameters of the bidirectional LLC converter of the above method embodiment.

[0132] Optionally, the present application also provides a computer product, which includes a computer-readable storage medium, in which a program is stored, and the program is loaded and executed by a processor to implement the particle swarm optimization method for the resonant parameters of the bidirectional LLC converter of the above-mentioned method embodiment.

[0133] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0134] The above embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A particle swarm optimization method for resonant parameters of a bidirectional LLC converter, characterized in that: The method comprises: Establishing an LLC full-bridge converter loss model. The LLC full-bridge converter loss model is used to calculate the total power loss of the LLC full-bridge converter in forward and reverse operation, based on the inductance ratio and quality factor. The total power loss of the LLC full-bridge converter in forward and reverse operation is the sum of the power loss of the resonant-side MOS transistor in forward and reverse operation, the power loss of the non-resonant-side MOS transistor in forward and reverse operation, the power loss of the resonant cavity in forward and reverse operation, and the power loss of the transformer in forward and reverse operation. Through mathematical derivation of the resonant circuit, the inductance ratio and quality factor are used as replacement variables for the resonant inductance, excitation inductance, and resonant capacitance. The gain of the LLC full-bridge converter is calculated and the range of inductance ratio values ​​that meet the gain requirements and the range of quality factor values ​​that meet the soft switching conditions are solved, including: Gain satisfaction: ; and The calculation formula is as follows: ; in, and is the highest and lowest voltage of the battery, is the DC bus voltage, is the turns ratio of the transformer; under no-load conditions, the quality factor is 0, the gain formula is as follows: ;in is the inductance ratio, is the normalized frequency; In order to ensure that the gain of the LLC full-bridge converter can meet the minimum requirement, the normalized frequency Take the maximum value ,at this time: ； Solve to obtain the inductance ratio that meets the gain requirements scope; In order to ensure that the LLC full-bridge converter can achieve soft switching, that is, to ensure that the main switch is turned on at zero voltage, the imaginary part of the input impedance needs to be zero. The corresponding critical conditions are as follows: ； in, is the maximum value of the quality factor, at full load, let , is the minimum value of the normalized frequency, and is substituted into the above formula, combined with the following gain requirements: ； Solve to obtain the quality factor that meets the soft switching conditions The value range of Based on the LLC full-bridge converter loss model and the obtained inductance ratio and quality factor ranges, the inductance ratio and quality factor are continuously updated through the particle swarm optimization algorithm until the loss of the LLC full-bridge converter is minimized and no longer changes. The resonant inductance, excitation inductance, and resonant capacitance corresponding to the inductance ratio and quality factor at this time are determined as the optimal parameters.

2. The particle swarm optimization method for resonant parameters of a bidirectional LLC converter according to claim 1, characterized in that: The establishment of the LLC full-bridge converter loss model includes: Normalization sets the switching frequency; Inductance ratio and quality factor are introduced to calculate the key current parameters of the LLC full-bridge converter at the forward resonant frequency point. The key current parameters include the effective value of the resonant current, the maximum value of the excitation current, and the effective value of the secondary current; The total power loss of the converter in forward and reverse operation is calculated based on the calculated key current parameters.

3. The particle swarm optimization method for resonant parameters of a bidirectional LLC converter according to claim 1, characterized in that: Based on the LLC full-bridge converter loss model and the obtained value ranges of the inductance ratio and the quality factor, the inductance ratio and the quality factor are continuously updated by a particle swarm optimization algorithm until the loss of the LLC full-bridge converter is minimized and no longer changes, and the resonant inductance, the excitation inductance, and the resonant capacitance corresponding to the inductance ratio and the quality factor at this time are determined as optimal parameters, including: Establish an LLC full-bridge converter simulation model on MATLAB / SIMULINK, define the design parameters of the LLC full-bridge converter and the model parameters of the LLC full-bridge converter loss model; After defining the design parameters of the LLC full-bridge converter and the model parameters of the LLC full-bridge converter loss model, the loss model parameters are substituted into the loss model of the LLC full-bridge converter to obtain the sum of the forward working loss and the reverse working loss of the LLC full-bridge converter; The particle swarm algorithm is used for optimization and substituted into the LLC full-bridge converter simulation model for simulation calculation. The sum of the forward working loss and reverse working loss of the LLC full-bridge converter is obtained. The algorithm is iterated continuously until the loss of the LLC full-bridge converter is minimized and no longer changes. The resonant inductance, excitation inductance, and resonant capacitance corresponding to the inductance ratio and quality factor at this time are determined and used as the optimal parameters in the LLC full-bridge converter.

4. A particle swarm optimization system for resonant parameters of a bidirectional LLC converter, characterized in that: include: A loss model establishment module is used to establish a loss model for an LLC full-bridge converter. The LLC full-bridge converter loss model is used to calculate the total power loss of the LLC full-bridge converter in forward and reverse operation under the premise of introducing the inductance ratio and quality factor. The total power loss of the LLC full-bridge converter in forward and reverse operation is the sum of the power loss of the resonant-side MOS tube in forward and reverse operation, the power loss of the non-resonant-side MOS tube in forward and reverse operation, the power loss of the resonant cavity in forward and reverse operation, and the power loss of the transformer in forward and reverse operation. A value range determination module is used to use the inductance ratio and the quality factor as replacement variables for the resonant inductance, the excitation inductance, and the resonant capacitance through mathematical deduction of the resonant circuit; Calculate the gain of the LLC full-bridge converter and solve for the range of inductance ratios that meet the gain requirements and the range of quality factors that meet the soft switching conditions, including: Gain satisfaction: ; and The calculation formula is as follows: ; in, and is the highest and lowest voltage of the battery, is the DC bus voltage, is the turns ratio of the transformer; under no-load conditions, the quality factor is 0, the gain formula is as follows: ;in is the inductance ratio, is the normalized frequency; In order to ensure that the gain of the LLC full-bridge converter can meet the minimum requirement, the normalized frequency Take the maximum value ,at this time: ； Solve to obtain the inductance ratio that meets the gain requirements scope; In order to ensure that the LLC full-bridge converter can achieve soft switching, that is, to ensure that the main switch is turned on at zero voltage, the imaginary part of the input impedance needs to be zero. The corresponding critical conditions are as follows: ； in, is the maximum value of the quality factor, at full load, let , is the minimum value of the normalized frequency, and is substituted into the above formula, combined with the following gain requirements: ； Solve to obtain the quality factor that meets the soft switching conditions The value range of The parameter update module is used to continuously update the inductance ratio and quality factor based on the LLC full-bridge converter loss model and the obtained value range of the inductance ratio and quality factor through a particle swarm optimization algorithm until the loss of the LLC full-bridge converter is minimized and no longer changes. The resonant inductance, excitation inductance, and resonant capacitance corresponding to the inductance ratio and quality factor at this time are determined as the optimal parameters.

5. An electronic device, characterized in that: The device includes a processor and a memory; the memory stores a program, and the program is loaded and executed by the processor to implement a particle swarm optimization method for resonant parameters of a bidirectional LLC converter according to any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that The storage medium stores a program, which, when executed by a processor, is used to implement a particle swarm optimization method for resonant parameters of a bidirectional LLC converter according to any one of claims 1 to 3.

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