LLC resonant parameter forward design method, device, equipment, medium and program product

Abstract

The present invention discloses a method, device, equipment, medium and program product for forward design of LLC resonant parameters. The method comprises: constructing a resonant mathematical model according to information of components participating in resonance in an LLC resonant converter, constructing a phase plane model of the LLC resonant converter based on the resonant mathematical model, constructing an objective function according to the phase plane model, calculating state trajectory parameters based on the objective function, and performing parameter design on the LLC resonant converter according to the state trajectory parameters; because the present invention realizes state trajectory simulation of the LLC resonant cavity by constructing a phase plane model of the LLC resonant converter, thereby realizing the design of LLC resonant parameters through the coordinates of each state point on the phase plane, effectively reducing the parameter design complexity of the converter, improving the parameter design efficiency, and effectively improving the performance of the LLC resonant converter.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a method, device, equipment, medium and program product for forward design of LLC resonance parameters. Background Art

[0002] With the vigorous promotion of new energy power generation and electric vehicles, the LLC resonant converter has been widely used in DC-DC conversion due to its good soft switching characteristics and voltage regulation control. The parameter design of the LLC resonant cavity directly determines the output characteristics of the converter. There are two main types of existing LLC parameter designs, including frequency domain design and time domain design.

[0003] The existing design scheme in the frequency domain mainly adopts the fundamental wave analysis method to consider the maximum voltage gain and Q value to select and determine the resonant capacitor (Cr), resonant inductor (Lr) and excitation inductor (Lm). First of all, the fundamental wave analysis method can have a good approximate analysis effect at the resonance point. Thanks to the fact that the resonant current is similar to a sine wave under this working condition, the harmonic content has almost no effect on the impedance characteristics of the resonant tank. However, when it deviates from the resonance point, especially when considering the maximum voltage gain, the resonant tank is no longer a sine wave. Ignoring the influence of harmonics on the resonant tank is obviously not accurate enough, which will cause the designed parameters to lose the monotonicity of control under extreme working conditions, resulting in control instability. The existing design method that considers the influence of harmonics at the deviated resonance point in the time domain analysis has a relatively complex calculation process, the description process is not intuitive, and the conditions of each converter must be analyzed separately, which increases the complexity of the design. Therefore, the current LLC resonant parameter design currently relies mainly on engineering experience, and the design process is complicated, resulting in low efficiency in resonant parameter design, which seriously affects the performance of LLC converters. Summary of the invention

[0004] The main purpose of the present invention is to provide a method, device, equipment, medium and program product for forward design of LLC resonant parameters, aiming to solve the technical problem that the prior art relies on engineering experience, the design process is complicated, resulting in low efficiency of resonant parameter design and seriously affecting the performance of LLC converter.

[0005] To achieve the above object, the present invention provides a method for forward designing LLC resonant parameters, which is applied to an LLC resonant converter and comprises the following steps:

[0006] Constructing a resonance mathematical model according to information of components participating in resonance in the LLC resonant converter;

[0007] Constructing a phase plane model of the LLC resonant converter based on the resonant mathematical model;

[0008] constructing an objective function according to the phase plane model;

[0009] State trajectory parameters are calculated based on the objective function, and parameters of the LLC resonant converter are designed according to the state trajectory parameters.

[0010] Optionally, the resonance mathematical model includes a binary resonance mathematical model and a ternary resonance mathematical model, and the binary resonance mathematical model includes:

[0011]

[0012] in, and are the midpoint voltages of the inverter bridge arm and the rectifier bridge arm of the LLC resonant converter, is the transformer turns ratio parameter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the resonant capacitor voltage;

[0013] The three-element resonance model includes:

[0014]

[0015] in, is the inverter arm midpoint voltage of the LLC resonant converter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the magnetizing inductance, is the resonant capacitor voltage.

[0016] Optionally, constructing a phase plane model of the LLC resonant converter based on the resonant mathematical model includes:

[0017] The resonance mathematical model is solved to obtain expressions of the resonant inductor current and the resonant capacitor voltage, wherein the expressions include a binary resonance expression and a ternary resonance expression, and the binary resonance expression includes:

[0018]

[0019] The three-element resonance expression includes:

[0020]

[0021] in, and are the midpoint voltages of the inverter bridge arm and the rectifier bridge arm of the LLC resonant converter, is the transformer turns ratio parameter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the resonant capacitor voltage, is the binary resonant characteristic impedance, is the three-element resonant characteristic impedance, and is the initial state value, is the initial bridge arm midpoint current, is the initial bridge arm midpoint voltage;

[0022] The expression is processed to obtain the relational expression of the initial state value:

[0023]

[0024]

[0025] in, and Determined based on the initial state value, and is the trajectory radius of the state variable on the phase plane model;

[0026] A phase plane model of the LLC resonant converter is constructed based on the relationship, wherein the ordinate of the phase plane model is the resonant inductor current, and the abscissa is the resonant capacitor voltage.

[0027] Optionally, constructing an objective function according to the phase plane model includes:

[0028] Constructing a gain characteristic relationship of the LLC resonant converter according to the phase plane model, wherein the gain characteristic relationship includes a resonance cavity trajectory constraint relationship of the LLC resonant converter under variable frequency control, a magnetic constraint relationship of the excitation inductance being clamped by the output voltage, an electrical constraint relationship of the input port and the output port of the LLC resonant converter, a time constraint relationship within a half cycle, and a geometric constraint relationship;

[0029] The gain characteristic relationship is normalized to obtain an objective function.

[0030] Optionally, the calculating state trajectory parameters based on the objective function, and performing parameter design on the LLC resonant converter according to the state trajectory parameters, includes:

[0031] Initialize particle parameters, wherein the particle parameters include the particle position, particle velocity and particle boundary of each particle in the particle group, the particle position is the function value of the objective function, the particle velocity is the gradient of the objective function, and the particle boundary is determined based on a geometric constraint relationship;

[0032] Calculating the current fitness of each particle according to the objective function, and updating the particle position and particle velocity of each particle until the current fitness meets the preset convergence condition, and determining the target output parameter of the particle swarm;

[0033] A state trajectory parameter is determined based on the target output parameter, and parameters of the LLC resonant converter are designed according to the state trajectory parameter.

[0034] Optionally, the performing parameter design on the LLC resonant converter according to the state trajectory parameters includes:

[0035] Determine the voltage gain parameter and current gain parameter of the LLC resonant converter:

[0036]

[0037]

[0038] in, is the maximum voltage gain, is the output voltage, is the minimum value of the input voltage, is the transformer turns ratio, is the maximum current, is the resonant impedance, is the minimum load resistance;

[0039] Acquire constraints of the LLC resonant converter based on the voltage gain parameter and the current gain parameter, wherein the constraints include operating mode boundary conditions, soft switching constraints, zero voltage switching conditions, and capacitor withstand voltage constraints;

[0040] Determine the resonance parameter selection range according to the constraint conditions;

[0041] Constructing a loss assessment model based on power loss information of the LLC resonant converter;

[0042] constructing an adaptability function according to the loss assessment model;

[0043] The LLC resonant converter is parameter designed based on the resonance parameter selection range, the adaptability function and the state trajectory parameters.

[0044] In addition, to achieve the above-mentioned purpose, the present invention also proposes an LLC resonance parameter forward design device, the LLC resonance parameter forward design device comprising:

[0045] A mathematical model building module, used for building a resonance mathematical model according to information of components involved in resonance in the LLC resonant converter;

[0046] A phase plane construction module, used to construct a phase plane model of the LLC resonant converter based on the resonant mathematical model;

[0047] An objective function construction module, used for constructing an objective function according to the phase plane model;

[0048] A parameter design module is used to calculate state trajectory parameters based on the objective function and perform parameter design on the LLC resonant converter according to the state trajectory parameters.

[0049] In addition, to achieve the above-mentioned purpose, the present application also proposes an LLC resonant parameter forward design device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the LLC resonant parameter forward design method as described above.

[0050] In addition, to achieve the above objectives, the present application also proposes a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the LLC resonant parameter forward design method as described above are implemented.

[0051] In addition, to achieve the above-mentioned purpose, the present application also provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the LLC resonant parameter forward design method as described above are implemented.

[0052] The present invention constructs a resonant mathematical model according to information of components participating in resonance in an LLC resonant converter, constructs a phase plane model of the LLC resonant converter based on the resonant mathematical model, constructs an objective function according to the phase plane model, calculates state trajectory parameters based on the objective function, and performs parameter design on the LLC resonant converter according to the state trajectory parameters; because the present invention realizes state trajectory simulation of the LLC resonant cavity by constructing a phase plane model of the LLC resonant converter, and thus realizes the design of LLC resonant parameters through the coordinates of each state point on the phase plane, the parameter design complexity of the converter is effectively reduced, the parameter design efficiency is improved, and the performance of the LLC resonant converter is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The accompanying drawings herein are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the description, are used to explain the principles of the present application.

[0054] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0055] Figure 1 It is a structural schematic diagram of an LLC resonance parameter forward design device in a hardware operating environment involved in an embodiment of the present invention;

[0056] Figure 2 It is a schematic flow chart of the first embodiment of the LLC resonant parameter forward design method of the present invention;

[0057] Figure 3 Schematic diagram of the structure of an LLC resonant converter in an embodiment of the LLC resonant parameter forward design method of the present invention;

[0058] Figure 4 It is a schematic diagram of a circular trajectory phase plane model of an LLC resonant converter in an embodiment of the LLC resonant parameter forward design method of the present invention;

[0059] Figure 5 It is a schematic diagram of an elliptical trajectory phase plane model of an LLC resonant converter in an embodiment of the LLC resonant parameter forward design method of the present invention;

[0060] Figure 6 A schematic diagram of the state trajectory in the phase plane model in an embodiment of the LLC resonant parameter forward design method of the present invention;

[0061] FIG7 (a) is a schematic diagram of the effective value of the primary-side current of the LLC resonant converter under different transformation ratios;

[0062] FIG7 (b) is a schematic diagram of the effective value of the secondary-side current of the LLC resonant converter under different transformation ratios;

[0063] Figure 8 Schematic diagram of optimal parameters in an embodiment of the LLC resonant parameter forward design method of the present invention;

[0064] Fig. 9 Schematic diagram of the LLC resonance parameter design process in an embodiment of the LLC resonance parameter forward design method of the present invention;

[0065] Fig.10 It is a structural block diagram of the first embodiment of the LLC resonance parameter forward design device of the present invention.

[0066] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0067] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0068] Reference Figure 1 , Figure 1 The figure is a schematic diagram of the structure of an LLC resonance parameter forward design device for a hardware operating environment involved in an embodiment of the present invention.

[0069] like Figure 1 As shown, the LLC resonance parameter forward design device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display), an input unit such as a keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a wireless fidelity (Wireless-Fidelity, WI-FI) interface). The memory 1005 may be a high-speed random access memory (RandomAccess Memory, RAM), or a stable non-volatile memory (Non-Volatile Memory, NVM), such as a disk storage. The memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0070] Those skilled in the art will understand that Figure 1 The structure shown in the figure does not constitute a limitation on the LLC resonant parameter forward design device, and may include more or less components than those shown in the figure, or combine certain components, or arrange the components differently.

[0071] like Figure 1 As shown, the memory 1005 as a computer-readable storage medium may include an operating system, a network communication module, a user interface module, and an LLC resonance parameter forward design program.

[0072] exist Figure 1In the LLC resonant parameter forward design device shown, the network interface 1004 is mainly used for data communication with the network server; the user interface 1003 is mainly used for data interaction with the user; the processor 1001 and the memory 1005 in the LLC resonant parameter forward design device of the present invention can be set in the LLC resonant parameter forward design device, and the LLC resonant parameter forward design device calls the LLC resonant parameter forward design program stored in the memory 1005 through the processor 1001, and executes the LLC resonant parameter forward design method provided by the embodiment of the present invention.

[0073] The embodiment of the present invention provides a method for forward designing LLC resonance parameters, referring to Figure 2 , Figure 2 FIG. 4 is a flow chart of the first embodiment of the LLC resonant parameter forward design method of the present invention.

[0074] In this embodiment, the method is applied to an LLC resonant converter, and the LLC resonant parameter forward design method includes the following steps:

[0075] Step S10: constructing a resonance mathematical model according to information of components participating in resonance in the LLC resonant converter.

[0076] In some embodiments, the structure of the LLC resonant converter can refer to Figure 3 , Figure 3 The schematic diagram of the LLC resonant converter structure is shown in Figure 2. The LLC resonant converter can be composed of three parts: the primary side switch full bridge, the LLC resonant cavity and the secondary side uncontrolled rectifier bridge. The designed operating frequency range is 100~200kHz. Among them, the primary side full bridge is composed of 4 SiC MOSFETs, namely the front bridge arm T1, T2 and the rear bridge arm T3, T4. Each SiC MOSFET is usually composed of a power transistor, parasitic capacitors C1, C2, C3, C4 and body anti-parallel diodes VD1, VD2, VD3, VD4. The resonant cavity part includes inductors Lr, Lm, capacitors Cr and high-frequency transformers, where Lm is replaced by the high-frequency transformer excitation inductance, Cr and Lr are the resonant capacitor and resonant inductor respectively, and n is the isolation transformer ratio. The secondary side adopts an uncontrolled rectifier full bridge, which is composed of 4 Schottky diodes D1, D2, D3, and D4.

[0077] It should be noted that the execution subject of this embodiment may be a computing service device with data processing, network communication and program running functions, such as a computer or a controller, or a terminal electronic device capable of realizing the above functions. The following takes the LLC resonant parameter forward design device (referred to as the design device) as an example to illustrate this embodiment and the following embodiments.

[0078] It should be noted that in this embodiment, the component information may be the electrical characteristic information of the type of the resonant component. For example, assuming the switching frequency is , the transformer turns ratio is n:1, and the midpoint voltages of the inverter bridge arm and the rectifier bridge arm of the converter are v ab and v cd , is the resonant capacitor, is the resonant inductor, is the magnetizing inductance, the resonant frequency It can be expressed as:

[0079]

[0080] Binary resonant angular frequency for:

[0081]

[0082] Three-element resonance angular frequency for:

[0083]

[0084] Binary resonant characteristic impedance for:

[0085]

[0086] Three-element resonance characteristic impedance for:

[0087]

[0088] Furthermore, in order to improve the calculation accuracy, the resonance mathematical model includes a binary resonance mathematical model and a ternary resonance mathematical model, and the binary resonance mathematical model includes:

[0089]

[0090] in, and are the midpoint voltages of the inverter bridge arm and the rectifier bridge arm of the LLC resonant converter, is the transformer turns ratio parameter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the resonant capacitor voltage;

[0091] The three-element resonance model includes:

[0092]

[0093] in, is the inverter arm midpoint voltage of the LLC resonant converter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the magnetizing inductance, is the resonant capacitor voltage.

[0094] It should be noted that for the PO mode of the LLC resonant converter, there are binary resonance and ternary resonance processes at the same time. If the analytical expression of the state variable is solved directly, the operation path of the variable cannot be intuitively reflected, the calculation complexity increases, and it is difficult to improve the actual control strategy. Therefore, this embodiment can construct a binary resonance mathematical model and a ternary resonance mathematical model, and then solve the binary resonance mathematical model and the ternary resonance mathematical model.

[0095] Step S20: constructing a phase plane model of the LLC resonant converter based on the resonant mathematical model.

[0096] It should be noted that the phase plane model may be a state parameter trajectory model of the LLC resonant converter, the ordinate of the phase plane model is the resonant inductor current, and the abscissa is the resonant capacitor voltage.

[0097] Furthermore, in order to intuitively reflect the running path of the state trajectory and thus accurately construct the phase plane model, the above step S20 may include:

[0098] Step S201: solving the resonance mathematical model to obtain expressions of the resonance inductor current and the resonance capacitor voltage;

[0099] Step S202: Process the expression to obtain a relational expression of the initial state value;

[0100] Step S203: constructing a phase plane model of the LLC resonant converter based on the relationship, wherein the ordinate of the phase plane model is the per-unit value of the resonant inductor current. i LrN , the horizontal axis is the per unit value of the resonant capacitor voltage v CrN .

[0101] It should be noted that the expression includes a binary resonance expression and a ternary resonance expression, and the binary resonance expression includes:

[0102]

[0103] The three-element resonance expression includes:

[0104]

[0105] in, and are the midpoint voltages of the inverter bridge arm and the rectifier bridge arm of the LLC resonant converter, is the transformer turns ratio parameter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the resonant capacitor voltage, is the binary resonant characteristic impedance, is the three-element resonant characteristic impedance, and is the initial state value, is the initial bridge arm midpoint current, is the initial bridge arm midpoint voltage;

[0106] It should be noted that for variable frequency control, the midpoint voltage of the bridge arm may be:

[0107]

[0108]

[0109] It should be noted that the relationship between the initial state value is:

[0110]

[0111]

[0112] in, and Determined based on the initial state value, and is the trajectory radius of the state variable on the phase plane model. It can be observed that the state trajectory in the binary resonance stage is part of a circle, and the state trajectory in the ternary resonance stage is part of an ellipse. is the voltage base value, the binary resonance characteristic impedance The impedance base value is normalized. The resonant inductor current normalized value can be established The vertical axis is the resonant capacitor voltage per unit value. The plane coordinate system reference for the horizontal axis Figure 4 and Figure 5 , Figure 4 and Figure 5 It is the phase plane model diagram of LLC resonant converter, where Figure 4 is a circular trajectory model, Figure 5 It is an elliptical trajectory model.

[0113] In some embodiments, reference Figure 6 , Figure 6 It is a schematic diagram of the state trajectory in the phase plane model. The state point runs from point B to point C for half a switching cycle, so point C is the point where T1 and T4 are turned on, and T2 and T3 are turned off; point B is the point where T1 and T4 are turned off, and T2 and T3 are turned on; point A is the point where the resonant inductor current is exactly equal to the excitation current, the rectifier bridge current is naturally turned off when it passes through zero, and the excitation inductance is no longer clamped by the output voltage, so it is the point from binary resonance to ternary resonance.

[0114] Step S30: constructing an objective function according to the phase plane model.

[0115] It can be understood that this embodiment facilitates subsequent analysis by calculating the gain characteristics of the LLC converter in a steady state, wherein: Figure 6 Point A of the state trajectory satisfies the circle equation, refer to the following scalarized trajectory constraint equation:

[0116]

[0117] Point B satisfies the ellipse equation, refer to the following scalarized trajectory constraint equation:

[0118]

[0119] in, is the horizontal coordinate of the point in the phase plane, is the vertical coordinate of the point, is the binary resonant characteristic impedance, is the three-element resonant characteristic impedance.

[0120] Figure 6 The CA segment in the state trajectory is charged, the excitation current increases linearly, and the excitation current at points C and A is equal to the resonant current, referring to the following magnetic constraint equation where the excitation inductance is clamped by the output voltage:

[0121]

[0122] in, is the binary resonance angular frequency, is the magnetizing inductance, The electrical angle of the CA segment state trajectory. y 2 Corresponding to the per-unit value of the resonant inductor current at point C, y 1 Corresponding to the per-unit value of the resonant inductor current at point A.

[0123] The resonant tank of the CA segment provides charge to the output capacitor, while the AB segment does not. The KCL in the half cycle refers to the electrical constraint equation of the converter input port as follows:

[0124]

[0125] in, is the resonant capacitor value, is the per unit value of the resonant capacitor voltage corresponding to point A, is the per-unit value of the resonant capacitor voltage at point C, is the average value of the output current, is the switching frequency. Corresponding to the per-unit value of the resonant inductor current at point C. is the binary resonance angular frequency, is the magnetizing inductance. n Indicates the transformation ratio of the transformer.

[0126] During the half cycle, the input current flows through , then the average charge in the half cycle is reflected as the change of the capacitor voltage. Refer to the following electrical constraint equation of the converter output port:

[0127]

[0128] in, is the average value of the input current, is the per-unit value of the resonant capacitor voltage at point C, is the per-unit value of the resonant capacitor voltage at point C, is the switching frequency.

[0129] Within a half-cycle, time is conserved, refer to the time constraint equation within the following half-cycle:

[0130]

[0131] in, is the electrical angle of the CA segment state trajectory, is the electrical angle of the AB segment state trajectory. is the binary resonance angular frequency, is the ternary resonance angular frequency. is the switching angular frequency.

[0132] The geometric relationship of the state trajectory refers to the following electrical angle calculation formula:

[0133]

[0134]

[0135] in, is the per unit value of the resonant capacitor voltage at point B, is the per unit value of the resonant capacitor voltage at point A. is the per-unit value of the resonant inductor current at point B, is the per-unit value of the resonant inductor current at point A. M is the per-unit value of the output voltage converted to the high voltage side.

[0136] Furthermore, in order to accurately construct the objective function, the above step S30 may include:

[0137] Step S31: constructing a gain characteristic relationship of the LLC resonant converter according to the phase plane model;

[0138] Step S32: normalize the gain characteristic relationship to obtain an objective function.

[0139] It should be noted that the gain characteristic relationship includes the resonance cavity trajectory constraint relationship of the LLC resonant converter under variable frequency control, the magnetic constraint relationship of the excitation inductance being clamped by the output voltage, the electrical constraint relationship of the input port and output port of the LLC resonant converter, the time constraint relationship within a half cycle, and the geometric constraint relationship.

[0140] It should be noted that, in this embodiment, the objective function group can be obtained by processing the above formula:

[0141]

[0142]

[0143]

[0144]

[0145]

[0146] in, You can Very easy to use So the original system of equations can be taken as Solve as iterative variables. Only two variables are left to form a transcendental equation. The numerical solution depends on the selection of initial values ​​and the setting of learning rate, and its calculation results may not converge. Define the objective function:

[0147]

[0148] The constraints are:

[0149]

[0150] Step S40: Calculating state trajectory parameters based on the objective function, and performing parameter design on the LLC resonant converter according to the state trajectory parameters.

[0151] It can be understood that, in this embodiment, the electrical angle and the trajectory radius (eg Figure 6 The electrical angle and , and the trajectory radius ) to determine the state trajectory parameters.

[0152] In some embodiments, the design device can solve the state trajectory parameters through a particle swarm optimization algorithm (Particle Swarm Optimization, PSO).

[0153] Furthermore, in order to accurately solve the state trajectory parameters, the above step S40 may include:

[0154] Step S401: Initialize particle parameters;

[0155] Step S402: Calculate the current fitness of each particle according to the objective function, and update the particle position and particle velocity of each particle until the current fitness meets the preset convergence condition, and determine the target output parameter of the particle swarm;

[0156] Step S403: determining state trajectory parameters based on the target output parameters, and performing parameter design on the LLC resonant converter according to the state trajectory parameters.

[0157] It should be noted that the particle parameters include the particle position, particle velocity and particle boundary of each particle in the particle group, the particle position is the function value of the objective function, the particle velocity is the gradient of the objective function, and the particle boundary is determined based on the geometric constraint relationship.

[0158] It is understandable that in the phase plane model, if the electrical angle can be solved and and radius The value of , then the resonant cavity state trajectory is uniquely determined and can be passed. Therefore, all particles are actually electrical angles and And the radius The particle velocity represents the gradient of the objective function, and the particle position represents the function value of the objective function. When the position of the particle swarm converges to a very small value, the trajectory is determined, and the relationship between the control amount and the output amount is also determined. Therefore, the particle swarm algorithm is used to solve the transcendental equations. The boundary of the particle is given by the state trajectory geometric constraint of the PO mode.

[0159] In some embodiments, the design device solves the state trajectory parameters by a particle swarm optimization algorithm, and the solving steps are as follows:

[0160] 1. Initialization: Randomly generate the initial position and velocity of the particle swarm. Each particle has a random position and velocity, which are usually randomly distributed in the solution space during initialization;

[0161] 2. Evaluation: Calculate the fitness of each particle (i.e., the objective function value) according to the objective function;

[0162] 3. Update the personal optimal solution: If the fitness of the current particle is better than its own historical optimal fitness, update the personal optimal solution;

[0163] 4. Update the global optimal solution: If the fitness of the current particle is better than the optimal fitness in the group, update the global optimal solution;

[0164] 5. Update speed and position: adjust the speed and position of each particle according to the speed update formula;

[0165] 6. Repeat iterations: Repeat steps 2 to 5 according to the stopping criteria (such as maximum number of iterations or convergence of the objective function) until the stopping condition is met.

[0166] Furthermore, in order to accurately design LLC resonance parameters, the above step S40 may include:

[0167] Determining a voltage gain parameter and a current gain parameter of the LLC resonant converter;

[0168] Acquire a constraint condition of the LLC resonant converter based on the voltage gain parameter and the current gain parameter;

[0169] Determine the resonance parameter selection range according to the constraint conditions;

[0170] Constructing a loss assessment model based on power loss information of the LLC resonant converter;

[0171] constructing an adaptability function according to the loss assessment model;

[0172] The LLC resonant converter is parameter designed based on the resonance parameter selection range, the adaptability function and the state trajectory parameters.

[0173] It should be noted that, first of all, the converter is considered to work in PO mode. When the converter enters PON mode, it is easy to enter the non-monotonic region of variable frequency control, causing control instability. First, ensure that the PO mode can still be maintained under the maximum voltage gain and maximum load. The corresponding voltage on the excitation inductance at point B is lower than the value of the output voltage converted to the primary side. The voltage gain parameter and current gain parameter refer to the following formula:

[0174]

[0175]

[0176] in, is the maximum voltage gain, is the output voltage, is the minimum value of the input voltage, is the transformer turns ratio, is the maximum current, is the resonant impedance, is the minimum load resistance.

[0177] It should be noted that the constraints include working mode boundary conditions, soft switching constraints, zero voltage switching conditions and capacitor withstand voltage constraints. The voltage on the excitation inductor is:

[0178]

[0179] The voltage on the exciting inductor should be less than the output voltage converted to the primary side. The constraint is:

[0180]

[0181] in, is the voltage on the magnetizing inductor, and nVo is the value of the output voltage converted to the primary side.

[0182] Therefore, the boundaries of the PO mode and the PON mode are:

[0183]

[0184]

[0185] in, is the voltage of the LLC resonant converter under boundary conditions, is the inductance ratio, is the per-unit value of the switching frequency, is the voltage gain, is the phase difference.

[0186] The constraints for soft switching are:

[0187]

[0188]

[0189] in, is the parasitic output capacitance of the switch tube, V inmin is the minimum voltage input, t deadband is the dead time of the upper and lower tubes of the inverter bridge arm. Zr is the binary characteristic impedance, I ZVS.minTo achieve the minimum current value for soft switching.

[0190] The value of each K can be fixed, and whether the ZVS condition is met can be determined by changing Zr. Since the larger the Zr, the smaller the resonant tank current, the more difficult it is to achieve soft switching. r When the ZVS condition cannot be achieved after reaching a certain value, ZVS cannot be achieved subsequently.

[0191] The withstand voltage of the resonant capacitor is , exceeding this requirement, it can be considered that the resonant tank parameter design is unreasonable, and the capacitor withstand voltage constraint is:

[0192]

[0193] in, is the maximum withstand voltage of the resonant capacitor, M is the voltage gain, and r1 is the radius of the CA segment trajectory circle.

[0194] The above constraints can determine the optional range of the resonance tank parameters, but it is still not specific enough. It is necessary to establish an adaptive function to further screen the options within the range.

[0195] In some embodiments, the design device can establish an adaptability function, and the power loss of the LLC converter includes conduction loss (conduction loss of the inverter bridge, the rectifier bridge, and the copper loss of the transformer), switching loss (mainly turn-off loss due to achieving ZVS) and core loss (mainly resonant inductance and iron loss of the transformer).

[0196] The loss assessment model in the time domain is established as follows:

[0197] Conduction loss on the primary side:

[0198]

[0199] The secondary side conduction loss is:

[0200]

[0201] The iron loss of the transformer is:

[0202]

[0203] The fitness function is:

[0204]

[0205] in, is the effective value of the transformer primary current, is the effective value of the secondary current of the transformer. R DS.on is the on-state resistance of the inverter bridge switch tube, rCr , r Lr , r Cu.Pri , r Cu.sec They are the parasitic resistance of the resonant capacitor, the parasitic resistance of the resonant inductor, the parasitic resistance of the primary winding of the transformer, and the parasitic resistance of the secondary winding of the transformer. V F is the conduction voltage drop of the rectifier bridge diode, r F is the on-state resistance of the diode, Kh is the magnetic loss coefficient of the magnetic core, B ac is the AC magnetic flux density, f s is the switching frequency, M core is the volume of the core, and the exponential term is the coefficient of the core.

[0206] Selecting parameters based on the primary current and secondary current can achieve the lowest current loss, so the effective value of the current calculated by the trajectory is:

[0207]

[0208] Through the state track can be brought in Figure 6 The ordinates of points C and A in the mid-phase plane model are solved as follows:

[0209]

[0210] Among them, a, b, c and d are the coefficients of the effective value of the primary current, k is the inductance ratio, f n is the normalized switching frequency.

[0211] Therefore, its effective value can be calculated as follows. By simplifying the square term through the double angle formula, the primary current can be calculated:

[0212]

[0213]

[0214] The time domain equation of the secondary current is:

[0215]

[0216] For each set of resonant parameters, the time domain expression of the current can be obtained, and the graphs of the effective values ​​of the primary and secondary currents under different transformation ratios can be drawn, as shown in Figure 7 (a) and Figure 7 (b). Figure 7 (a) is a schematic diagram of the effective value of the primary current of the LLC resonant converter under different transformation ratios, and Figure 7 (b) is a schematic diagram of the effective value of the secondary current of the LLC resonant converter under different transformation ratios. Finally, the optimal parameters under the same characteristic impedance are obtained, as shown in Figure 7 (a). Figure 8 , Figure 8 Schematic diagram of the optimal parameters.

[0217] In some embodiments, reference Fig. 9 , Fig. 9 The LLC resonant parameter forward design process diagram is shown in FIG. The LLC resonant parameter forward design method may include: inputting initial parameters, which may include the maximum output voltage, the minimum output voltage, the target output voltage, the minimum operating frequency, the maximum input voltage, and the maximum output current, etc.; inputting the initial inductance ratio k and the characteristic impedance Zr, performing per-unit processing, calculating the state trajectory parameters of the LLC resonant converter in the PO mode by using the particle swarm algorithm, judging whether the state trajectory parameters are in the PO mode, judging whether the ZVS condition is met, and judging the resonant frequency f n Is it lower than the minimum resonant frequency f? nmin , calculate the effective value of the primary and secondary currents, and calculate the loss P loss , determine whether the loss is lower than the recorded value, determine whether the k value overflows, and obtain the optimal LLC resonance design parameters based on the above judgment results.

[0218] This embodiment constructs a resonant mathematical model according to the information of components participating in resonance in the LLC resonant converter, constructs a phase plane model of the LLC resonant converter based on the resonant mathematical model, constructs an objective function according to the phase plane model, calculates state trajectory parameters based on the objective function, and performs parameter design on the LLC resonant converter according to the state trajectory parameters; since this embodiment realizes the state trajectory simulation of the LLC resonant cavity by constructing the phase plane model of the LLC resonant converter, the design of the LLC resonant parameters is realized through the coordinates of each state point on the phase plane, which effectively reduces the parameter design complexity of the converter, improves the parameter design efficiency, and effectively improves the performance of the LLC resonant converter.

[0219] In addition, an embodiment of the present invention further proposes a computer-readable storage medium, on which an LLC resonant parameter forward design program is stored. When the LLC resonant parameter forward design program is executed by a processor, the steps of the LLC resonant parameter forward design method described above are implemented.

[0220] The computer-readable storage medium provided in the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM: Random Access Memory), a read-only memory (ROM: Read Only Memory), an erasable programmable read-only memory (EPROM: Erasable Programmable Read Only Memory or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM: CD-Read Only Memory), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency: Radio Frequency), etc., or any suitable combination of the above.

[0221] The computer-readable storage medium may be included in the LLC resonant parameter forward design device; or may exist independently without being assembled into the LLC resonant parameter forward design device.

[0222] In addition, an embodiment of the present invention further provides a computer program product, including an LLC resonance parameter forward design program, which implements the steps of the LLC resonance parameter forward design method described above when executed by a processor.

[0223] The specific implementation of the computer program product of the present invention is basically the same as the embodiments of the above-mentioned LLC resonant parameter forward design method, and will not be repeated here.

[0224] Reference Fig.10 , Fig.10 It is a structural block diagram of the first embodiment of the LLC resonance parameter forward design device of the present invention.

[0225] like Fig.10 As shown, the LLC resonance parameter forward design device proposed in the embodiment of the present invention includes:

[0226] A mathematical model building module 10 is used to build a resonance mathematical model according to information of components participating in resonance in the LLC resonant converter;

[0227] A phase plane construction module 20, configured to construct a phase plane model of the LLC resonant converter based on the resonant mathematical model;

[0228] An objective function construction module 30, used to construct an objective function according to the phase plane model;

[0229] The parameter design module 40 is used to calculate the state trajectory parameters based on the objective function, and perform parameter design on the LLC resonant converter according to the state trajectory parameters.

[0230] Furthermore, the resonance mathematical model includes a binary resonance mathematical model and a ternary resonance mathematical model, and the binary resonance mathematical model includes:

[0231]

[0232] in, and are the midpoint voltages of the inverter bridge arm and the rectifier bridge arm of the LLC resonant converter, is the transformer turns ratio parameter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the resonant capacitor voltage;

[0233] The three-element resonance model includes:

[0234]

[0235] in, is the inverter arm midpoint voltage of the LLC resonant converter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the magnetizing inductance, is the resonant capacitor voltage.

[0236] Furthermore, the phase plane building module 20 is also used to solve the resonance mathematical model to obtain expressions of the resonant inductor current and the resonant capacitor voltage, wherein the expressions include a binary resonance expression and a ternary resonance expression, and the binary resonance expression includes:

[0237]

[0238] The three-element resonance expression includes:

[0239]

[0240] in, and are the midpoint voltages of the inverter bridge arm and the rectifier bridge arm of the LLC resonant converter, is the transformer turns ratio parameter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the resonant capacitor voltage, is the binary resonant characteristic impedance, is the three-element resonant characteristic impedance, and is the initial state value, is the initial bridge arm midpoint current, is the initial bridge arm midpoint voltage;

[0241] The expression is processed to obtain the relational expression of the initial state value:

[0242]

[0243]

[0244] in, and Determined based on the initial state value, and is the trajectory radius of the state variable on the phase plane model;

[0245] A phase plane model of the LLC resonant converter is constructed based on the relationship, wherein the ordinate of the phase plane model is the resonant inductor current, and the abscissa is the resonant capacitor voltage.

[0246] Furthermore, the objective function construction module 30 is also used to construct a gain characteristic relationship of the LLC resonant converter according to the phase plane model, wherein the gain characteristic relationship includes a resonant cavity trajectory constraint relationship of the LLC resonant converter under variable frequency control, a magnetic constraint relationship of the excitation inductance clamped by the output voltage, an electrical constraint relationship of the input port and output port of the LLC resonant converter, a time constraint relationship and a geometric constraint relationship within a half cycle; the gain characteristic relationship is normalized to obtain an objective function.

[0247] Furthermore, the parameter design module 40 is also used to initialize particle parameters, and the particle parameters include the particle position, particle velocity and particle boundary of each particle in the particle swarm, the particle position is the function value of the objective function, the particle velocity is the gradient of the objective function, and the particle boundary is determined based on the geometric constraint relationship; the current fitness of each particle is calculated according to the objective function, and the particle position and particle velocity of each particle are updated until the current fitness meets the preset convergence condition, and the target output parameter of the particle swarm is determined; the state trajectory parameter is determined based on the target output parameter, and the parameter design of the LLC resonant converter is performed according to the state trajectory parameter.

[0248] Furthermore, the parameter design module 40 is also used to determine the voltage gain parameter and the current gain parameter of the LLC resonant converter:

[0249]

[0250]

[0251] in, is the maximum voltage gain, is the output voltage, is the minimum value of the input voltage, is the transformer turns ratio, is the maximum current, is the resonant impedance, is the minimum load resistance;

[0252] Acquire constraints of the LLC resonant converter based on the voltage gain parameter and the current gain parameter, wherein the constraints include operating mode boundary conditions, soft switching constraints, zero voltage switching conditions, and capacitor withstand voltage constraints;

[0253] Determine the resonance parameter selection range according to the constraint conditions;

[0254] Constructing a loss assessment model based on power loss information of the LLC resonant converter;

[0255] constructing an adaptability function according to the loss assessment model;

[0256] The LLC resonant converter is parameter designed based on the resonance parameter selection range, the adaptability function and the state trajectory parameters.

[0257] This embodiment constructs a resonant mathematical model according to the information of components participating in resonance in the LLC resonant converter, constructs a phase plane model of the LLC resonant converter based on the resonant mathematical model, constructs an objective function according to the phase plane model, calculates state trajectory parameters based on the objective function, and performs parameter design on the LLC resonant converter according to the state trajectory parameters; since this embodiment realizes the state trajectory simulation of the LLC resonant cavity by constructing the phase plane model of the LLC resonant converter, the design of the LLC resonant parameters is realized through the coordinates of each state point on the phase plane, which effectively reduces the parameter design complexity of the converter, improves the parameter design efficiency, and effectively improves the performance of the LLC resonant converter.

[0258] The LLC resonant parameter forward design device provided by the present application adopts the LLC resonant parameter forward design method in the above embodiment, and can solve the technical problems of LLC resonant parameter forward design. Compared with the prior art, the beneficial effects of the LLC resonant parameter forward design device provided by the present application are the same as the beneficial effects of the LLC resonant parameter forward design method provided by the above embodiment, and other technical features in the LLC resonant parameter forward design device are the same as the features disclosed in the above embodiment method, which will not be repeated here.

[0259] It should be understood that the above is only an example and does not constitute any limitation on the technical solution of the present invention. In specific applications, technicians in this field can make settings as needed, and the present invention does not limit this.

[0260] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of the present invention. In practical applications, technicians in this field can select part or all of them according to actual needs to achieve the purpose of the present embodiment, and no limitation is made here.

[0261] In addition, for technical details not described in detail in this embodiment, reference may be made to the LLC resonant parameter forward design method provided in any embodiment of the present invention, which will not be described in detail here.

[0262] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0263] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0264] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as a read-only memory / random access memory, a magnetic disk, or an optical disk), and includes a number of instructions for enabling a terminal device (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0265] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the protection scope of the present invention.

Claims

1. A method for forward design of LLC resonance parameters, characterized in that: The method is applied to an LLC resonant converter, and the LLC resonant parameter forward design method comprises: Constructing a resonance mathematical model according to information of components participating in resonance in the LLC resonant converter; Constructing a phase plane model of the LLC resonant converter based on the resonant mathematical model; constructing an objective function according to the phase plane model; Calculating state trajectory parameters based on the objective function, and performing parameter design on the LLC resonant converter according to the state trajectory parameters; The constructing the objective function according to the phase plane model comprises: Constructing a gain characteristic relationship of the LLC resonant converter according to the phase plane model, wherein the gain characteristic relationship includes a resonance cavity trajectory constraint relationship of the LLC resonant converter under variable frequency control, a magnetic constraint relationship of the excitation inductance being clamped by the output voltage, an electrical constraint relationship of the input port and the output port of the LLC resonant converter, a time constraint relationship within a half cycle, and a geometric constraint relationship; Normalizing the gain characteristic relationship to obtain an objective function; The calculating state trajectory parameters based on the objective function and performing parameter design on the LLC resonant converter according to the state trajectory parameters includes: Initialize particle parameters, wherein the particle parameters include the particle position, particle velocity and particle boundary of each particle in the particle group, the particle position is the function value of the objective function, the particle velocity is the gradient of the objective function, and the particle boundary is determined based on a geometric constraint relationship; Calculating the current fitness of each particle according to the objective function, and updating the particle position and particle velocity of each particle until the current fitness meets the preset convergence condition, and determining the target output parameter of the particle swarm; A state trajectory parameter is determined based on the target output parameter, and parameters of the LLC resonant converter are designed according to the state trajectory parameter.

2. The LLC resonance parameter forward design method according to claim 1, characterized in that: The resonance mathematical model includes a binary resonance mathematical model and a ternary resonance mathematical model, and the binary resonance mathematical model includes: in, and are the midpoint voltages of the inverter bridge arm and the rectifier bridge arm of the LLC resonant converter, is the transformer turns ratio parameter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the resonant capacitor voltage; The three-element resonance mathematical model includes: in, is the inverter arm midpoint voltage of the LLC resonant converter, is the resonant capacitor, is the resonant inductor, is the resonant inductor current, is the magnetizing inductance, is the resonant capacitor voltage.

3. The LLC resonance parameter forward design method according to claim 2, characterized in that: The step of constructing a phase plane model of the LLC resonant converter based on the resonant mathematical model comprises: The resonance mathematical model is solved to obtain expressions of the resonant inductor current and the resonant capacitor voltage, wherein the expressions include a binary resonance expression and a ternary resonance expression, and the binary resonance expression includes: The three-element resonance expression includes: in, and are the midpoint voltages of the inverter bridge arm and the rectifier bridge arm of the LLC resonant converter, is the transformer turns ratio parameter, is the resonant inductor current, is the resonant capacitor voltage, is the binary resonant characteristic impedance, is the three-element resonant characteristic impedance, and is the initial state value, is the initial bridge arm midpoint current, is the initial bridge arm midpoint voltage, represents the binary resonant angular frequency, represents the ternary resonance angular frequency; The expression is processed to obtain the relational expression of the initial state value: in, and Determined based on the initial state value, and is the trajectory radius of the state variable on the phase plane model; A phase plane model of the LLC resonant converter is constructed based on the relationship, wherein the ordinate of the phase plane model is the resonant inductor current, and the abscissa is the resonant capacitor voltage.

4. The LLC resonance parameter forward design method according to claim 1, characterized in that: The performing parameter design on the LLC resonant converter according to the state trajectory parameters comprises: Determine the voltage gain parameter and current gain parameter of the LLC resonant converter: in, is the maximum voltage gain, is the output voltage, is the minimum value of the input voltage, is the transformer turns ratio, is the maximum current, is the resonant impedance, is the minimum load resistance; Acquire constraints of the LLC resonant converter based on the voltage gain parameter and the current gain parameter, wherein the constraints include operating mode boundary conditions, soft switching constraints, zero voltage switching conditions, and capacitor withstand voltage constraints; Determine the resonance parameter selection range according to the constraint conditions; Constructing a loss assessment model based on power loss information of the LLC resonant converter; constructing an adaptability function according to the loss assessment model; The LLC resonant converter is parameter designed based on the resonance parameter selection range, the adaptability function and the state trajectory parameters.

5. A forward design device for LLC resonance parameters, characterized in that: The LLC resonance parameter forward design device comprises: A mathematical model building module, used for building a resonance mathematical model according to information of components involved in resonance in the LLC resonant converter; A phase plane construction module, used to construct a phase plane model of the LLC resonant converter based on the resonant mathematical model; An objective function construction module, used for constructing an objective function according to the phase plane model; A parameter design module, used for calculating state trajectory parameters based on the objective function, and performing parameter design on the LLC resonant converter according to the state trajectory parameters; The objective function construction module is further used to construct a gain characteristic relationship of the LLC resonant converter according to the phase plane model, wherein the gain characteristic relationship includes a resonance cavity trajectory constraint relationship of the LLC resonant converter under variable frequency control, a magnetic constraint relationship of the excitation inductance being clamped by the output voltage, an electrical constraint relationship of the input port and the output port of the LLC resonant converter, and a time constraint relationship and a geometric constraint relationship within a half cycle; the gain characteristic relationship is normalized to obtain an objective function; The parameter design module is also used to initialize particle parameters, and the particle parameters include the particle position, particle velocity and particle boundary of each particle in the particle group, the particle position is the function value of the objective function, the particle velocity is the gradient of the objective function, and the particle boundary is determined based on the geometric constraint relationship; the current fitness of each particle is calculated according to the objective function, and the particle position and particle velocity of each particle are updated until the current fitness meets the preset convergence condition, and the target output parameter of the particle group is determined; the state trajectory parameter is determined based on the target output parameter, and the parameter design of the LLC resonant converter is performed according to the state trajectory parameter.

6. An LLC resonance parameter forward design device, characterized in that: The LLC resonant parameter forward design device comprises: a memory, a processor, and an LLC resonant parameter forward design program stored in the memory and executable on the processor, wherein the LLC resonant parameter forward design program is configured to implement the LLC resonant parameter forward design method as described in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores an LLC resonance parameter forward design program, and when the LLC resonance parameter forward design program is executed by a processor, the LLC resonance parameter forward design method according to any one of claims 1 to 4 is implemented.

8. A computer program product, characterized in that The computer program product comprises an LLC resonance parameter forward design program, and when the LLC resonance parameter forward design program is executed by a processor, the steps of the LLC resonance parameter forward design method according to any one of claims 1 to 4 are implemented.

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