Frequency conversion phase shift control-based resonant converter light load voltage gain determination method

Abstract

The invention discloses a resonant converter light load voltage gain determination method based on frequency conversion phase shift control and related equipment, and the method comprises the steps: building an optimization model of a circuit working waveform ignoring a resonance transition process under a light load condition, and the optimization model is used for representing the working waveform characteristics of a circuit during light load; setting a first condition, a second condition and a third condition based on the optimization model, and deriving a function relationship of the voltage gain influenced by the phase shift duty ratio, the dead time and the switching frequency based on the optimization model, the three assumed conditions and the established equation relationship; and based on the function relationship and the zero-voltage turn-on condition of the critical switching tube, determining the optimal phase shift duty ratio and the dead time which meet the given voltage gain requirement, so as to solve the problems of overlarge design margin, low efficiency and inaccurate voltage gain calculation of the dead time, and further improve the voltage gain calculation precision under the light-load working condition.

Description

Technical Field

[0001] This application relates to the field of power electronic converter performance optimization and control technology, specifically to a method for determining the light-load voltage gain of a resonant converter based on frequency conversion phase shift control and related equipment. Background Technology

[0002] Currently, LLC resonant converters are widely used in the field of high-reliability DC power supplies due to their advantages such as soft switching, high power density, and low electromagnetic interference. However, the dead-time design for achieving zero-voltage turn-on (ZVS) and zero-current turn-off (ZCS) of the switching transistors under light load conditions has always been a technical challenge. Although traditional frequency conversion phase-shift control strategies can narrow the frequency modulation range and optimize soft-switching performance, the existence of the lag arm and lead arm significantly increases the complexity of ZVS analysis under light load conditions. Existing methods often ignore the impact of dead time on duty cycle and voltage gain, resulting in problems such as excessive margin and reduced efficiency in dead-time design. Furthermore, they do not establish a direct correlation between voltage gain and dead time and phase-shift duty cycle, making it difficult to accurately determine the parameter combination that meets the voltage gain requirements and ZVS conditions. Summary of the Invention

[0003] The purpose of this application is to provide a method and related equipment for determining the voltage gain of a resonant converter under light load based on frequency conversion phase shift control. This method has the advantages of improving the accuracy of voltage gain calculation under light load conditions, optimizing dead time design, improving switching efficiency, and ensuring the stability of zero-voltage turn-on of the switching transistor.

[0004] This application provides a method for determining the voltage gain of a resonant converter under light load based on frequency conversion phase-shift control. The method includes: establishing an optimized model of the circuit operating waveform under light load conditions, ignoring the resonant transient process; the optimized model is used to characterize the operating waveform characteristics of the circuit under light load; and setting assumptions based on the optimized model, including: a first condition, the resonant current at the end of the dead time of the leading arm is equal to the excitation current; a second condition, the dead time of the leading arm achieves zero-voltage turn-on of the critical switch, and the resonant current of the dead time of the lagging arm is approximately equal to the excitation current; and a third condition, the dead time of the lagging arm is comparable to the dead time of the leading arm, making the dead time... It can be used as a single variable; based on the optimization model, the first condition, and the third condition, a first equation relationship between the resonant current and the excitation current at the critical moment of the dead zone is established; based on the optimization model, the second condition, and the third condition, a second equation relationship between voltage gain, dead time, and phase shift duty cycle is established; based on the optimization model, the three assumptions, and the established equation relationship, the functional relationship between voltage gain and phase shift duty cycle, dead time, and switching frequency is derived; based on the functional relationship and the zero-voltage turn-on condition of the critical switch, the optimal phase shift duty cycle and dead time that meet the given voltage gain requirement are determined.

[0005] Furthermore, this application also proposes that the optimization model for establishing the circuit operating waveform under light load conditions, ignoring the resonant transient process, includes: dividing the circuit into operating stages through time-domain analysis, wherein the operating stages are defined based on the optimization model as the hysteresis dead zone LCC resonant stage, the LC resonant stage, the forearm dead zone LCC resonant stage, and the LLC resonant circulating current stage; and establishing an optimization model for ignoring the resonant transient process under light load conditions based on the circuit operating waveforms of each operating stage.

[0006] Furthermore, this application also proposes that the assumptions set based on the optimization model include: setting assumptions using the characteristic information of the working waveforms of each working stage in the optimization model, so that the assumptions are consistent with the trend of the actual working waveforms of the circuit; wherein, the first condition corresponds to the current characteristic information at the end of the dead zone of the leading arm in the optimization model, the second condition corresponds to the zero-voltage turn-on characteristic information of the critical switch tube during the dead zone time in the optimization model, and the third condition corresponds to the correlation characteristic information between the dead zone time of the lagging arm and the leading arm in the optimization model.

[0007] Furthermore, this application also proposes that establishing the first equation relationship between the resonant current and the excitation current at the critical moment of the dead zone includes: at the end point of the dead zone of the advance arm, making the instantaneous value of the resonant current equal to the instantaneous value of the excitation current; the instantaneous value of the excitation current is determined by the current increase under the action of the phase shift duty cycle superimposed on the initial excitation current reverse value, wherein the current increase is proportional to the output voltage, the excitation inductance, the phase shift duty cycle, and the switching period.

[0008] Furthermore, this application also proposes that establishing the second equation relationship between voltage gain and dead time and phase shift duty cycle includes: establishing a positive correlation between voltage gain and the ratio of switching frequency to resonant frequency, such that the higher the switching frequency is relative to the resonant frequency, the greater the voltage gain tends to be; establishing a positive correlation between voltage gain and phase shift duty cycle, such that the voltage gain increases when the phase shift duty cycle increases; and establishing a negative correlation constraint relationship between voltage gain and normalized dead time, such that the voltage gain decreases when the proportion of dead time to the switching cycle increases.

[0009] Furthermore, this application proposes that the derivation of the functional relationship between voltage gain and phase shift duty cycle, dead time, and switching frequency includes: based on the dynamic balance characteristics of resonant current and excitation current in the first equation, and combined with the correlation law between voltage gain and various parameters in the second equation, an analysis result is obtained; the current change characteristics of each working stage in the optimization model and the influence of parasitic capacitance charging and discharging on energy transfer are incorporated into the analysis process to obtain the influence result; through segmented processing and integration of the time-domain waveform, the analysis result and the influence result are transformed into a quantitative relationship to form a functional relationship that can reflect the coordinated change of voltage gain with phase shift duty cycle, dead time, and switching frequency.

[0010] Furthermore, this application also proposes that, based on the functional relationship and the critical zero-voltage turn-on condition of the switch, determining the optimal phase-shift duty cycle and dead time to meet the given voltage gain requirement includes: analyzing the trend of voltage gain with phase-shift duty cycle and dead time in the functional relationship, defining the parameter value range to meet the given voltage gain requirement; introducing the critical zero-voltage turn-on condition of the switch within the parameter value range, and screening out parameter combinations that can achieve zero-voltage turn-on of the switch; and determining the phase-shift duty cycle and dead time that optimize voltage gain stability and switching efficiency from the combinations that meet the conditions.

[0011] Furthermore, this application also proposes that the third condition further includes: when deriving the functional relationship between voltage gain and each parameter, setting the leading arm dead time as a basic variable, and establishing a correlation between the lagging arm dead time and this basic variable; after the optimal value of the leading arm dead time is calculated through the functional relationship, according to the requirements for the lagging arm dead time in the third condition, adding a preset proportion of margin on the basis of the optimal value, thereby determining the lagging arm dead time, to ensure that the lagging arm switching transistor can achieve zero-voltage turn-on.

[0012] As can be seen from the above, the method and related equipment for determining the light-load voltage gain of a resonant converter based on frequency conversion phase-shift control provided in this application establish an optimization model under light-load conditions and set key assumptions. By combining the dynamic balance equation and parameter correlation, the voltage gain function is derived, and finally the optimal parameter combination that satisfies the voltage gain requirements and the zero-voltage turn-on condition of the switching transistor is determined. This solves the problems of excessive dead time design margin, low efficiency and inaccurate voltage gain calculation in the prior art. It has the advantages of improving the accuracy of voltage gain calculation under light-load conditions, optimizing dead time design, improving switching efficiency and ensuring the stability of zero-voltage turn-on of the switching transistor. Attached Figure Description

[0013] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments; Figure 1 The circuit structure diagram of the full-bridge LLC resonant converter provided in the embodiment of the present invention; Figure 2 A schematic diagram illustrating the steps of a method for determining the light-load voltage gain of a resonant converter based on frequency conversion phase-shift control, provided in an embodiment of the present invention. Figure 3 The waveform diagram of the full-bridge LLC resonant converter circuit provided in the embodiment of the present invention; Figure 4 The circuit waveform diagram of the optimized full-bridge LLC resonant converter provided in the embodiment of the present invention; Figure 5(a) is the equivalent circuit diagram of the t0-t1 stage of the hysteresis dead zone LCC resonance provided in the embodiment of the present invention; Figure 5(b) is the equivalent circuit diagram of the LC resonance stage t1-t2 provided in the embodiment of the present invention; Figure 5(c) is the equivalent circuit diagram of the forearm dead zone LCC resonance stage t2-t3 provided in the embodiment of the present invention; Figure 6 A flowchart illustrating the calculation method steps provided in this embodiment of the invention; Figure 7(a) is a three-dimensional graph of the function G=f1(Td,D) provided in an embodiment of the present invention; Figure 7(b) is a side cross-sectional view of the function G=f1(Td,D) provided in an embodiment of the present invention; Figure 8 This is a diagram showing the optimal duty cycle selection provided in an embodiment of the present invention. Figure 9(a) shows the simulation results of the rectifier bridge current and resonant current provided in the embodiment of the present invention; Figure 9(b) shows the simulation results of the voltage withstand by the switching transistor provided in the embodiment of the present invention; Figure 9(c) shows the simulation results of the output given voltage gain provided by the embodiment of the present invention. Detailed Implementation

[0015] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following drawings indicate similar items; therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0016] Currently, LLC resonant converters are widely used in high-reliability DC power supplies, but designing the dead time for achieving zero-voltage turn-on of the critical switch under light load conditions presents technical challenges. While traditional frequency converter phase-shift control strategies can optimize soft-switching performance, the presence of lag and lead arms significantly increases the complexity of analyzing the zero-voltage turn-on of the critical switch under light load conditions. Existing methods often neglect the impact of dead time on duty cycle and voltage gain, resulting in excessive dead time design margins and reduced efficiency. Furthermore, they fail to establish a direct correlation between voltage gain, dead time, and phase-shift duty cycle, making it difficult to accurately determine the parameter combination that satisfies both voltage gain requirements and the zero-voltage turn-on condition of the critical switch.

[0017] To address the aforementioned issues, a method is needed to simplify dead-time analysis under light load conditions and establish a direct correlation between voltage gain and key parameters. In existing technologies, the independent design of dead time and phase-shift duty cycle leads to difficulties in parameter matching, and neglecting the influence of the resonant transient process results in insufficient model accuracy. Therefore, the core issue is how to integrate key variables through model optimization to achieve precise voltage gain control while ensuring zero-voltage turn-on of the critical switch. By analyzing the simplified conditions of the circuit's operating waveform under light load conditions, and treating dead time and phase-shift duty cycle as co-variables, establishing a functional relationship between voltage gain and these two variables becomes a feasible approach to solving this problem.

[0018] Therefore, the purpose of this application is to provide a method and related equipment for determining the light-load voltage gain of a resonant converter based on frequency conversion phase shift control, aiming to provide a method for calculating the light-load voltage gain of a full-bridge LLC resonant converter considering the influence of dead time, so that the converter voltage gain... GThe expression is more accurate, providing a theoretical basis for the design of the dead time of LLC resonant converter under light load conditions, thereby reducing the difficulty of ZVS analysis within the dead time and improving the working efficiency of the converter.

[0019] refer to Figure 1 The circuit structure diagram of the present invention is as follows: Figure 1 As shown, the circuit consists of the H-bridge arm Q 1~ Q 4( Q 1, Q 3 constitutes the forearm. Q 2, Q 4 constitutes the lagging arm) L r C r Resonant unit, main transformer TX 1(Magnetic Inductance) L m ), rectifier bridge D 5~ D 8 and output filter capacitor C o Composition. Among them... D 1~ D 4 is the switching transistor Q 1~ Q 4-cell body diode, C oss1 ~ C oss4 For switching transistors Q 1~ Q Parasitic capacitance of 4. Under light load conditions, the LLC frequency converter phase shift control drive waveform and circuit operating waveform are as follows: Figure 2 As shown, Figure 2 The transient analysis showed several stages, including: 1. Lag arm dead zone. L r , C r , C oss Resonance (LCC resonance) stage t 0- t 1 , 2. L r , C r resonance( LC (Resonance) stage t 1 , - t 2; 3, Forearm dead zone L r , C r , C ossResonance (LCC resonance) stage t 2- t 2 , 4. The resonant current is equal to the excitation current, thus starting the circuit. L r , L m , C r Three-element resonance (LLC resonance) transition stage t 2 , - t 3; 5. The input voltage of the resonant cavity is zero, entering the LLC resonant circulating current stage. t 3- t 4. Resonant current at different stages i The Lr-stage abbreviation will be used for identification.

[0020] refer to Figure 2 , Figure 2 This is a schematic diagram illustrating the steps of a method for determining the light-load voltage gain of a resonant converter based on frequency conversion phase-shift control, as provided in an embodiment of the present invention; as shown below. Figure 2 As shown, the method for determining the light-load voltage gain of a resonant converter based on frequency conversion phase-shift control may include at least the following steps: Step 201: Establish an optimized model of the circuit operating waveform under light load conditions, ignoring the resonant transient process. The optimized model is used to characterize the operating waveform characteristics of the circuit under light load. Step 202: Set assumptions based on the optimization model. The assumptions include: First, the resonant current at the end of the dead zone of the leading arm is equal to the excitation current; Second, the dead zone of the leading arm achieves zero-voltage turn-on of the critical switching transistor, and the resonant current of the dead zone of the lagging arm is approximately equal to the excitation current; Third, the dead time of the lagging arm is comparable to that of the leading arm, so that the dead time can be used as a single variable. Step 203: Based on the optimization model, the first condition, and the third condition, establish the first equation relationship between the resonant current and the excitation current at the critical moment of the dead zone. Step 204: Based on the optimization model, the second condition, and the third condition, establish a second equation relating voltage gain to dead time and phase shift duty cycle. Step 205: Based on the optimization model, three assumptions, and the established equations, derive the functional relationship between voltage gain and phase shift duty cycle, dead time, and switching frequency. Step 206: Based on the functional relationship and the zero-voltage turn-on condition of the critical switch, determine the optimal phase shift duty cycle and dead time that meet the given voltage gain requirements.

[0021] The optimization model refers to the mathematical expression of waveform characteristics by dividing the circuit's operating stages through time-domain analysis. Specifically, it can adopt a stage division method of the lag arm dead zone LCC resonance stage, LC resonance stage, fore-arm dead zone LCC resonance stage, and LLC resonance circulating current stage to characterize the circuit's dynamic characteristics under light load. In the assumptions, the first condition constrains the current balance state at the end of the fore-arm dead zone, the second condition ensures the boundary for achieving zero-voltage turn-on of the critical switch, and the third condition simplifies the correlation between dead-time variables. The equations are established based on the current change law and energy conservation principle at each stage; for example, the first equation is derived by the current increase under the influence of the reverse value of the excitation current and the phase shift duty cycle. The derivation of the functional relationships integrates the synergistic effects of switching frequency, dead-time percentage, and phase shift duty cycle, forming a multivariate control model for voltage gain.

[0022] It is worth noting that the frequency conversion phase shift control strategy is the control method for frequency conversion phase shift, which can be used to drive the frequency conversion phase shift control waveform.

[0023] refer to Figure 3 , Figure 3 The following is a waveform diagram of the full-bridge LLC resonant converter circuit provided in an embodiment of the present invention; it can be seen that under light load conditions, the LLC frequency conversion phase shift control drive waveform and the circuit operating waveform are as follows: Figure 2 As shown, Figure 2 The transient analysis showed several stages, including: 1. Lag arm dead zone. L r , C r , C oss Resonance (LCC resonance) stage t 0- t 1 , 2. L r , C r resonance( LC (Resonance) stage t 1 , - t 2; 3, Forearm dead zone L r , C r , C oss Resonance (LCC resonance) stage t 2- t 2 , 4. The resonant current is equal to the excitation current, thus starting the circuit. L r , L m , Cr Three-element resonance (LLC resonance) transition stage t 2 , - t 3; 5. The input voltage of the resonant cavity is zero, entering the LLC resonant circulating current stage. t 3- t 4. Resonant current at different stages i The Lr-stage abbreviation will be used for identification.

[0024] Specifically, this method first divides the working process under light load conditions into four stages through time-domain analysis, constructing an optimization model that ignores the resonant transient process. Based on the model, three assumptions are set to transform complex waveform characteristics into quantifiable parameter relationships. At the end of the dead zone of the advance arm, a first equation is established by constraining the resonant current to equal the excitation current, where the excitation current is determined by the linear increase of the initial value superimposed on the phase-shift duty cycle. Combining the zero-voltage turn-on condition of the critical switch, a second equation is established between voltage gain and dead time and phase-shift duty cycle. By integrating the current change characteristics of each stage and the influence of parasitic capacitance charging and discharging, a functional relationship between voltage gain and three key parameters is finally formed. Based on this functional relationship, the optimal parameter combination is selected within the constraint of satisfying the zero-voltage turn-on of the critical switch to achieve a balance between voltage gain stability and switching efficiency.

[0025] Understandably, based on the above steps, this application can use time-domain analysis to analyze the voltage gain change of the full-bridge LLC resonant converter with frequency conversion phase-shift control strategy under light load conditions, ignore the LLC resonant transient process, optimize the circuit working waveform, and establish the following three assumptions: (1) At the end of the dead zone of the leading arm, the resonant current iLr(t3) is equal to the excitation current iLm(t3), i.e., the first condition; (2) The dead zone of the leading arm realizes the zero-voltage turn-on of the switching tube, and the resonant current of the dead zone of the lagging arm is approximately equal to the excitation current, but does not affect the clamping of the excitation inductor Lm by the output voltage Uo, i.e., the second condition; (3) The dead time of the lagging arm is comparable to the dead time of the leading arm, so the dead time can be used as an unknown variable Td. After the size of the leading arm dead zone is accurately calculated, the size of the lagging arm dead zone only needs to be increased by a certain margin, i.e., the third condition; Based on assumption (1), an equation relating the resonant current and the excitation current at the critical end of the dead zone was established. Based on assumption (2), an equation relating voltage gain to dead zone size and phase shift duty cycle was established. Based on the above three assumptions, the functional relationship between voltage gain G and parameters such as phase shift duty cycle D, dead time Td, and switching frequency fs is derived.

[0026] The full-bridge LLC resonant converter, based on the aforementioned assumptions, ensures symmetry of the excitation current within half a switching cycle, simplifying the calculation of the excitation current magnitude at critical moments. The full-bridge LLC resonant converter employs a frequency-shifting phase-shifting control strategy, which, compared to traditional frequency-shifting control strategies, reduces the difficulty of achieving ZVS analysis of the primary-side switching transistors within the dead time Td under light load conditions. The full-bridge LLC resonant converter analyzes the resonant current within the dead time, considering the impact of dead time on the duty cycle and light-load voltage gain, and establishes a functional relationship among these three factors. This allows for the identification of the optimal phase-shifting duty cycle and dead time that satisfy both ZVS and voltage gain requirements, providing a theoretical basis for the design of the LLC resonant converter's dead time and improving the converter's operating efficiency.

[0027] Compared with existing technologies, existing methods typically treat dead time and phase shift duty cycle as independent variables, leading to difficulties in parameter matching and the inability to establish an accurate voltage gain control model. This scheme integrates key variables through optimization modeling, and has the following advantages: (1) The optimization processing of the circuit operating waveform based on three assumptions causes less error in circuit voltage gain analysis than traditional optimization processing; (2) For the first time, it establishes the relationship between the converter voltage gain G and dead time of an LLC resonant converter under light load conditions using a frequency conversion phase shift control strategy. T d A direct functional relationship makes the voltage gain... G The expression is more accurate; (3) by establishing voltage gain G With phase shift duty cycle D Dead time T d and switching frequency f s By studying the functional relationship between them, we can find the optimal phase shift duty cycle and dead time that satisfy both ZVS and voltage gain requirements, providing a theoretical basis for the design of these parameters and improving the efficiency of the converter.

[0028] This enables the synergistic optimization of voltage gain and the zero-voltage turn-on condition of the critical switch. By establishing a multivariable functional relationship, the optimal combination of phase shift duty cycle and dead time that satisfies specific voltage gain requirements can be directly calculated, avoiding the efficiency loss caused by traditional trial-and-error methods. Simultaneously, the parameter selection mechanism based on critical conditions ensures reliable zero-voltage turn-on of the critical switch under light load conditions, improving the overall operating efficiency of the converter.

[0029] This application further proposes a method for determining the light-load voltage gain of a resonant converter based on frequency conversion phase-shift control. This method includes dividing the circuit into operating stages through time-domain analysis. The operating stages are defined by an optimization model as the hysteresis dead zone LCC resonant stage, the LC resonant stage, the fore-arm dead zone LCC resonant stage, and the LLC resonant circulating current stage. An optimization model is established based on the circuit operating waveforms of each operating stage to ignore the resonant transient process under light-load conditions.

[0030] Time-domain analysis refers to the segmented study of the dynamic behavior of a circuit over time. Specifically, this can be achieved by mathematically modeling the voltage and current waveforms of different operating modes within a switching cycle. By dividing the circuit into different stages, the interaction between resonant current and magnetizing current can be accurately captured. Operating stage segmentation involves decomposing the circuit operation into sub-processes with distinct physical characteristics. This can be achieved by identifying changes in the conduction state of the switching transistors and the energy transfer paths of the resonant components, for example, by defining them based on the dead zone states of the lagging and leading arms and the differences in the equivalent circuit structure of the resonant cavity. The optimization model refers to a simplified mathematical description of the circuit behavior under light load conditions. This can be achieved by ignoring the high-frequency resonant transient process and retaining key waveform characteristics, such as considering only the current change trend and energy transfer path during the steady-state phase.

[0031] Specifically, under light load conditions, the circuit's operating waveform is divided into four stages: the lag arm dead zone LCC resonance stage corresponds to the state where the resonant cavity is equivalent to an LCC structure after the lag arm switch is turned off; the LC resonance stage corresponds to the state where the lag arm switch is turned on and the resonant cavity is equivalent to an LC structure; the leading arm dead zone LCC resonance stage corresponds to the state where the resonant cavity is equivalent to an LCC structure after the leading arm switch is turned off; and the LLC resonant circulating current stage corresponds to the state where the leading arm switch is turned on and the resonant cavity is equivalent to an LLC structure. After the equivalent circuit model of each stage is established, by solving the current differential equations of each stage and matching the boundary conditions of adjacent stages, the dynamic relationship between the resonant current and the excitation current can be derived, thereby constructing an optimized model that ignores the high-frequency resonant transient process.

[0032] This application further proposes to set assumptions based on the characteristic information of the working waveforms of each working stage in the optimization model, so that the assumptions are consistent with the trend of the actual working waveforms of the circuit. The first condition corresponds to the current characteristic information at the end of the dead zone of the leading arm in the optimization model, the second condition corresponds to the zero-voltage turn-on characteristic information of the critical switch in the dead time in the optimization model, and the third condition corresponds to the correlation characteristic information between the dead time of the lagging arm and the leading arm in the optimization model.

[0033] The characteristic information of the operating waveform during the working phase refers to the variation law of current and voltage in different operating modes of the circuit. Specifically, it can be achieved by segmenting and modeling the waveforms of the lagging arm dead zone LCC resonance stage, LC resonance stage, leading arm dead zone LCC resonance stage, and LLC resonance circulating current stage using time-domain analysis. The assumption that the waveform trend is consistent with the actual operating waveform means that the set conditions must meet the current change rate, phase relationship, and energy transfer characteristics in the measured or simulated waveforms. This can be verified by comparing the deviation between the optimization model calculation results and the actual waveform data. The characteristic information of zero-voltage turn-on of the critical switch refers to the dynamic balance relationship between the resonant current and the charging and discharging of the parasitic capacitance during the dead time. This can be achieved by using the constraint that the resonant current equals the excitation current at the end of the dead time.

[0034] Specifically, during the LCC resonance stage in the lagging arm dead zone, the decay rate of the resonant current after the lagging arm switch is turned off is analyzed, and the correlation between the lagging arm dead zone time and the slope of the resonant current decrease is determined by combining the parasitic capacitance voltage change curve. During the LCC resonance stage in the leading arm dead zone, the current balance equation at the end of the leading arm dead zone (i.e., the first condition) is established based on the overlap characteristics of the resonant current and the excitation current during the reverse charging process. During the LLC resonant circulating current stage, the quantitative relationship between the phase shift duty cycle and the voltage gain is derived by tracking the linear growth law of the excitation current under the phase shift duty cycle. By transforming the waveform characteristics of each stage into mathematical constraints, the assumptions can accurately reflect the dynamic change process of the resonant current under light load conditions.

[0035] This application further proposes to establish a first equation relationship between the resonant current and the excitation current at the critical moment of the dead zone, including making the instantaneous value of the resonant current equal to the instantaneous value of the excitation current at the end of the dead zone of the lead arm; the instantaneous value of the excitation current is determined by the current increase under the action of the phase shift duty cycle superimposed on the initial excitation current reverse value, wherein the current increase is proportional to the output voltage, the excitation inductance, the phase shift duty cycle, and the switching period.

[0036] The instantaneous value of the resonant current equaling the instantaneous value of the excitation current refers to the instantaneous equilibrium between the resonant network current and the transformer excitation branch current at the end of the dead zone after the lead-arm switch is turned off (i.e., the specific manifestation of the first condition). This can be achieved by real-time detection of the current waveform or by calculating the critical point current value based on circuit parameters. Establishing this equilibrium state can avoid voltage spikes caused by sudden current changes at the end of the dead zone, ensuring that the lagging arm switch achieves the critical switch zero-voltage turn-on condition.

[0037] The current increase is determined by the output voltage, magnetizing inductance, phase shift duty cycle, and switching period, and can be quantified using a linear superposition model. For example, during the phase shift duty cycle, the change in magnetizing current can be expressed as the ratio of output voltage to magnetizing inductance multiplied by the product of phase shift duty cycle and switching period. This relationship allows the calculation of the current increase to be directly related to circuit parameters, providing a quantitative basis for dead-time optimization.

[0038] Specifically, at the end of the dead-time phase of the forearm, the instantaneous balance condition (first equation) between the resonant current and the magnetizing current is forcibly established. At this point, the initial reverse value of the magnetizing current is determined by the operating state of the first half of the switching cycle, while the current increment introduced by the phase-shift duty cycle reflects the dynamic adjustment of energy transfer under light load conditions. By modeling the current increase as a linear function of the output voltage, magnetizing inductance, phase-shift duty cycle, and switching cycle, the dynamic balance relationship of the current at the end of the dead time can be accurately described. The establishment of this equation allows the coupling effect between the dead time and the phase-shift duty cycle to be explicitly expressed, laying the foundation for subsequent joint optimization of voltage gain and dead time.

[0039] This application further proposes a second equation relating voltage gain to dead time and phase shift duty cycle, including: establishing a positive correlation between voltage gain and the ratio of switching frequency to resonant frequency, such that the higher the switching frequency is relative to the resonant frequency, the greater the voltage gain tends to be; establishing a positive correlation between voltage gain and phase shift duty cycle, such that the voltage gain increases when the phase shift duty cycle increases; and establishing a negative correlation constraint between voltage gain and normalized dead time, such that the voltage gain decreases when the proportion of dead time to the switching cycle increases.

[0040] The positive correlation between voltage gain and the ratio of switching frequency to resonant frequency means that voltage gain increases as the ratio of switching frequency to resonant frequency increases. This can be achieved using a linear function relationship between the frequency ratio and voltage gain, for example, by setting voltage gain equal to the frequency ratio multiplied by a proportionality coefficient. This relationship reflects the improvement in energy transfer efficiency under high-frequency operating modes. The positive correlation between voltage gain and phase shift duty cycle means that voltage gain increases linearly as the phase shift duty cycle increases. This can be achieved using the product of duty cycle and voltage gain, for example, by setting voltage gain equal to the product of duty cycle and a fixed coefficient. This relationship characterizes the regulatory effect of phase shift control on the energy distribution of the resonant cavity. The negative correlation between voltage gain and normalized dead time means that voltage gain decreases as the proportion of dead time to switching cycle increases. This can be achieved using the reciprocal relationship between normalized dead time and voltage gain, for example, by setting voltage gain equal to a fixed parameter divided by the normalized dead time. This relationship quantifies the suppression effect of energy loss during the dead time on the overall voltage gain.

[0041] Specifically, based on the optimized model and assumptions, a positive correlation function between voltage gain and frequency is established by analyzing the impact of switching frequency on the impedance characteristics of the resonant cavity. For example, when the switching frequency is higher than the resonant frequency, the resonant cavity exhibits inductive characteristics, and energy transfer efficiency is improved. Increasing the phase-shift duty cycle prolongs the effective power transfer phase, thus improving voltage gain through the positive correlation function between duty cycle and voltage gain. Normalized dead time, by relating it to the switching cycle, establishes a negative correlation constraint between dead time and voltage gain. For example, when the proportion of dead time to the switching cycle exceeds a threshold, the attenuation of the resonant current leads to increased energy loss, and the voltage gain decreases accordingly. These three relationships are integrated through algebraic operations into a second equation, forming an explicit mathematical expression between voltage gain and multiple variables.

[0042] This application further proposes the implementation of the third condition, which includes: when deriving the functional relationship between voltage gain and each parameter, setting the leading arm dead time as the basic variable, and establishing a correlation between the lagging arm dead time and this basic variable; after the optimal value of the leading arm dead time is calculated through the functional relationship, according to the requirements for the lagging arm dead time in the third condition, adding a certain proportion of margin to the optimal value to determine the lagging arm dead time, ensuring that the lagging arm switching transistor can achieve zero-voltage turn-on of the critical switching transistor.

[0043] The fundamental variable refers to the optimized calculation of the leading-arm dead time as an independent variable, which can be achieved through numerical iteration or analytical derivation. Using it as a core parameter simplifies the complexity of multi-variable coupling relationships. The correlation relationship refers to establishing a proportional constraint between the lagging-arm dead time and the leading-arm dead time (i.e., the core of the third condition), which can be achieved through linear superposition or coefficient correction to ensure coordination in time allocation. The margin refers to the additional time added to the calculated value to ensure the zero-voltage turn-on of the lagging-arm switch, which can be achieved through a fixed percentage or dynamic adjustment strategy to compensate for the effects of parasitic parameter differences and device characteristic fluctuations.

[0044] Specifically, when establishing the voltage gain function model, the leading-arm dead time is first parameterized as an independent variable, and the lagging-arm dead time is bound to it through a mathematical relationship (based on the third condition). After calculating the optimal solution for the leading-arm dead time based on the voltage gain requirement and the zero-voltage condition of the critical switch, the lagging-arm dead time is extended according to a preset scaling factor. For example, a 10%-20% time margin is added to the optimal solution, allowing the lagging-arm switch sufficient time to discharge parasitic capacitance during turn-off, thereby achieving the zero-voltage turn-on condition of the critical switch. In this process, the decoupling of the leading-arm and lagging-arm dead times reduces the dimensionality of parameter optimization, while the margin superposition mechanism effectively avoids the negative impact of device parameter discreteness on turn-on characteristics.

[0045] Specifically, refer to Figure 4 And Figure 5, Figure 4 Figure 5 shows the circuit waveforms of the optimized full-bridge LLC resonant converter provided in this embodiment of the invention; Figure 5(a) shows the equivalent circuit diagram of the lag arm dead zone LCC resonant stage t0-t1 provided in this embodiment of the invention; Figure 5(b) shows the equivalent circuit diagram of the LC resonant stage t1-t2 provided in this embodiment of the invention; Figure 5(c) shows the equivalent circuit diagram of the forearm dead zone LCC resonant stage t2-t3 provided in this embodiment of the invention; wherein, Figure 4 The circuit waveforms after optimization based on three assumptions are shown in Figure 5. Based on this, equivalent circuits in the complex frequency domain are established for each stage. By formulating mesh current equations for the equivalent circuits in the complex frequency domain for each stage, the resonant currents for the corresponding stages can be obtained. s The domain expression is derived, and then the time domain expression is obtained. According to Figure 5(a), the lag arm dead zone LCC resonance stage... t 0- t 1. Mesh equation: (1) in C oss2 = C oss4 = C oss , U ds ( t 0)= U in . We can obtain s Domain equations: (2) The time-domain equation is obtained through inverse Laplace transform: (3) in

[0046] According to Figure 5(b), the LC resonance stage t 1- t 2. Mesh equation: (4) s Domain equations: (5) Time-domain equations: (6) in

[0047] According to Figure 5(c), the LCC resonance stage of the forearm dead zone. t 2- t 3. Mesh equation: (7) in C oss1 = C oss3 = C oss , U ds ( t 2)= U in . s Domain equations: (8) Time-domain equations: (9) in,

[0048] Based on the established assumptions and combined with time-domain analysis, a method can be established using phase shift duty cycle. D Dead time T d Voltage gain G As an unknown quantity, the switching period T s resonant cavity parameters L m , L r , C r Parasitic capacitance C oss Main transformer turns ratio n and input voltage U in An equation relationship expressed as a known quantity.

[0049] Assumption 1 can be listed i Lr ( t 3)= i Lm ( t 3) Requires output i Lr ( t 3) According to formulas (6) and (9), we need to first obtain i Lr ( t 1) Due to the dead zone of the lagging arm t 0- t 1. The resonant current is approximately equal to the excitation current, then i Lr ( t 1)= i Lm ( t 1), and the magnetizing inductance is t 0- t Within 3 years, it has always been nU o Clamping, therefore in t 0- t Changes in excitation current within 3: (10) Considering the symmetry of the excitation current, we can conclude that: (11) The final excitation current is t 0- t The time-domain expression within 3: (12) It can then be determined that: (13) Substituting into formula (6), we get: (14) Substituting into formula (9), we get: (15) Combining formula (11), the equation obtained under assumption 1 is: (16) The resonant capacitor voltage U Cr ( t 1) with U Cr ( t To solve 2), we need to first solve for... UCr ( t 0), According to circuit analysis, we know that: (17) In the calculation of current integration, the resonant current during the LC resonant phase... i Lr-LC ( t Resonant current during the LCC resonant phase of the forearm dead zone i Lr-LCC ( t Linearization processing, circulation stage t 3- t 4 resonant current i Lr-LLC ( t The attenuation is relatively small, so it can be considered as a constant current. i Lr-LLC ( t 4)= i Lm ( t 3). For example Figure 4 As shown by the black dashed line. The final expression for the current integral: (18) It can be found that the integral contains i Lr ( t 2), According to formula (14), i Lr ( t 2) The expression contains U Cr ( t 1). And U Cr ( t 1) can be represented as: (19) Combining formulas (18) and (19), the final U Cr ( t 0) Expression: (20) Then find U Cr ( t 2) Expression: (twenty one) Based on assumption 2, and according to the law of charge conservation, the following equations can be derived: (twenty two) Based on the two equations (16) and (22) established by the assumptions, the unknown variables are eliminated. nU o This forms an implicit function equation, and then the electrical parameters are... i Lr ( t 2) U Cr ( t 1) and U Cr ( t Substituting the expressions for 2), namely formulas (13), (19), (20), and (21), into the equations, the DC voltage gain can be calculated. G The expression (23).

[0050] (twenty three) in: (twenty four) In the circuit analysis of the LLC resonant converter in the frequency conversion phase shift control mode, according to formula (23), the voltage gain is... G The expression for phase shift duty cycle D With dead time T d These two unknowns are related, but traditional frequency converter phase shift control circuit analysis ignores the dead zone, therefore the obtained voltage gain... G The expression is without T d Yes, but under light load conditions, T d The impact of changes in voltage gain cannot be ignored. Therefore, the voltage gain obtained in this invention... G The expression is more accurate. The flowchart of the proposed calculation method is as follows: Figure 6 As shown, Figure 6 A flowchart illustrating the calculation method steps provided in this embodiment of the invention.

[0051] refer to Figure 6 This application further proposes a method for deriving the functional relationship between voltage gain and phase shift duty cycle, dead time, and switching frequency. This method includes: based on the dynamic balance characteristics of resonant current and excitation current in the first equation, and combined with the correlation law between voltage gain and various parameters in the second equation; incorporating the current change characteristics of each operating stage in the optimization model, as well as the influence of parasitic capacitance charging and discharging on energy transfer, during the analysis; and transforming the above characteristics, laws, and influencing factors into quantitative relationships through segmented processing and integration of the time-domain waveform, forming a functional relationship that reflects the coordinated change of voltage gain with phase shift duty cycle, dead time, and switching frequency.

[0052] The dynamic balance characteristic refers to the equality of the instantaneous values ​​of the resonant current and the excitation current at the critical moment of the dead zone. This can be achieved by establishing an equation relating the instantaneous value of the resonant current to the increase in the excitation current. This characteristic ensures the continuity of energy transfer at the end of the dead zone. The current variation characteristics of each operating stage refer to the rise and fall patterns of the current in the lag arm dead zone LCC resonant stage, LC resonant stage, forearm dead zone LCC resonant stage, and LLC resonant circulating current stage. This can be achieved by extracting the slope and amplitude changes of each stage through time-domain waveform analysis. This characteristic quantifies the contribution of different stages to the voltage gain. The impact of parasitic capacitance charging and discharging on energy transfer refers to the energy loss caused by the charging and discharging of the switching junction capacitance during the dead zone. This can be achieved by calculating the correction term of the resonant current to the capacitor voltage change. This impact is used to correct the accuracy of the voltage gain calculation model. The segmented processing and integration of time-domain waveforms refers to establishing an overall correlation after independently analyzing the waveforms of different operating stages. This can be achieved by solving the equations of each stage simultaneously using a piecewise linearization method. This processing method eliminates the interference of the transient process on the model complexity. The formation of functional relationships refers to the transformation of current balance conditions, voltage gain correlation laws, and the influence of parasitic parameters into mathematical expressions. Specifically, this can be achieved by deriving explicit relationships between voltage gain and phase shift duty cycle, dead time, and switching frequency through multivariable simultaneous equations. These relationships form the basis for constructing parameter co-optimization.

[0053] Specifically, in establishing the voltage gain function relationship, the constraints on dead time and phase shift duty cycle are first determined based on the dynamic balance equation (first equation) between resonant current and excitation current. Then, considering the current variation characteristics of each operating stage, the contribution weights of different stages to the voltage gain are derived. During this process, the charging and discharging energy of parasitic capacitance is quantified as a voltage gain correction term and superimposed onto the basic voltage gain equation. Finally, through piecewise integration of the time-domain waveform, dead time, phase shift duty cycle, and switching frequency are treated as independent variables to construct a three-variable coupled voltage gain function model. This model can be analytically expressed as a mathematical relationship where voltage gain is negatively correlated with normalized dead time, positively correlated with phase shift duty cycle, and positively correlated with the ratio of switching frequency to resonant frequency.

[0054] This application further proposes a method for determining the optimal phase shift duty cycle and dead time to meet a given voltage gain requirement based on functional relationships and the zero-voltage turn-on condition of the critical switch. The method includes analyzing the trend of voltage gain with phase shift duty cycle and dead time in the functional relationship, defining the range of parameter values ​​that meet the given voltage gain requirement; introducing the zero-voltage turn-on condition of the critical switch within this range, and screening out parameter combinations that can achieve the zero-voltage turn-on of the critical switch; and determining the phase shift duty cycle and dead time that optimize voltage gain stability and switching efficiency from the combinations that meet the condition.

[0055] The functional relationship refers to the mathematical expression established through the optimization model relating voltage gain to phase shift duty cycle, dead time, and switching frequency. This can be achieved using piecewise linearized equations or polynomial fitting methods. This relationship quantifies the synergistic effect of different parameter combinations on voltage gain. The critical zero-voltage turn-on condition for the switch refers to the constraint that the voltage across the switch must drop to zero before conduction (the core of the second condition). This can be achieved by detecting the current threshold when parasitic capacitance discharge is complete. This condition ensures the minimization of switching losses.

[0056] Specifically, under light load conditions, the parameter variation trend curves are first plotted based on the established voltage gain function relationship. Feasible solutions for phase shift duty cycle and dead time are then selected by setting a target voltage gain range. Subsequently, a zero-voltage turn-on condition for the critical switch is superimposed on the feasible solution set to eliminate candidate parameters that cannot achieve soft switching. Finally, a multi-objective optimization algorithm is used to evaluate the efficiency and voltage gain stability of the remaining parameter combinations, selecting the phase shift duty cycle and dead time combination that optimizes the overall system performance. For example, a particle swarm optimization algorithm can be used to weight the voltage gain fluctuation amplitude and switching losses to determine the optimal solution that satisfies the constraints. based on Figure 6 In some embodiments, the simulation parameters are designed as shown in Table 1: Table 1 Parameter Design

[0057] The simulated rated output resistance is set to R o-R =48.4Ω, rated power is P R = U o 2 / R o-R =529W, taking 5% light load, that is, the output resistance in the simulation experiment is taken as R o-L =968Ω. Substitute the above parameters into formula (23) and set the calculation interval as shown in Table 2: Table 2 Calculation of Interval Parameters

[0058] The voltage gain can be obtained. G With dead time T d Phase shift duty cycle D Functional Relationship G = f 1( T d , DThe three-dimensional image is shown in Figure 7. From Figure 7(a), it can be clearly seen that as the phase shift duty cycle increases... D As the phase shift duty cycle increases, the output voltage gain also increases. This can be clearly seen in Figure 7(b) with a fixed phase shift duty cycle. D With dead time T d As the voltage increases, the output voltage gain also increases slowly, but as... D Increase dead time T d Its ability to affect output voltage gain will become increasingly smaller.

[0059] Meanwhile, by substituting the parameters and calculation intervals from Table 1 into the formula (22) derived under assumption 2, we obtain the implicit constraint function for achieving zero-voltage turn-on of the switching transistor. f 2( T d , D Given that )=0, plot the corresponding implicit function curve using Matlab. Based on Table 1, given the output voltage gain requirement... G =0.8, referring to Figure 7, draw the corresponding cross-sectional curve. f 1( T d , D )=0.8, such as Figure 8 As shown. From Figure 8 From this, we can know the dead time corresponding to the intersection of the two curves. T d1 With optimal phase shift duty cycle D 1. It can achieve both zero-voltage turn-on of the switching transistor and meet the given voltage gain requirements.

[0060] according to Figure 8 ,Pick D 1 = 0.17, forearm dead time T d1 =150ns, hysteresis arm dead time T d2 =200ns. Based on the design parameters in Table 1, Saber simulation was performed. The simulation results are shown in Figure 9. From Figure 9(a), it can be seen that... t At 3 o'clock, i rect ≈0. The operating waveform of the resonant current is similar to... Figure 3 Almost identical. As shown in Figure 9(b), the dead time of the leading and lagging arms enables zero-voltage turn-on of the switching transistor. As shown in Figure 9(c), the output voltage... U o =160±5V, which is basically consistent with the given voltage gain requirement.

[0061] This application further proposes a computer program product, including a computer program that, when executed by a processor, implements the steps of a method for determining the light-load voltage gain of a resonant converter based on frequency conversion phase-shift control. The steps include establishing an optimized model of the circuit operating waveform under light-load conditions, ignoring the resonant transient process; setting three assumptions (first condition, second condition, and third condition); establishing a first equation relationship between the resonant current and the excitation current; establishing a second equation relationship between the voltage gain and the dead time and phase-shift duty cycle; deriving the functional relationship between the voltage gain and the phase-shift duty cycle, dead time, and switching frequency; and determining the optimal parameter combination based on the zero-voltage turn-on condition of the critical switch.

[0062] Computer program products refer to storage media or transmission carriers containing executable code, specifically implemented as USB flash drives, optical discs, or server download links, used for storing and transmitting program instructions. Processor execution refers to running the instruction sequence in the program through a central processing unit or application-specific integrated circuit (ASIC), specifically implemented using a multi-core processor or embedded controller, controlling data flow and computation processes by parsing instructions. The method for determining the light-load voltage gain of a resonant converter based on frequency conversion phase-shift control refers to an algorithmic flow that establishes mathematical relationships between parameters based on an optimization model and three assumptions. Specifically, it can be achieved through piecewise time-domain analysis and solving dynamic balance equations, used to derive the quantitative relationship between voltage gain, dead time, and phase-shift duty cycle.

[0063] This application further proposes an electronic device including one or more processors and a memory associated with one or more processors, the memory being used to store program instructions, which, when read and executed by one or more processors, perform the steps of a method for determining the light-load voltage gain of a resonant converter based on frequency conversion phase-shift control (i.e., the method of claims 1 to 8).

[0064] Here, "processor" refers to an integrated circuit chip with logical operation capabilities, specifically a central processing unit (CPU) or a digital signal processor (DSP), used to parse and execute instruction sequences stored in memory. "Memory" refers to a semiconductor device with data storage capabilities, specifically flash memory or dynamic random access memory (DRAM), used to permanently store program code containing the voltage gain determination algorithm. "Program instructions" refers to machine language code executable by the processor, specifically written in binary instruction set format, used to translate the control logic of the methods in claims 1 to 8 into executable hardware operations.

[0065] The above are merely embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for determining the light-load voltage gain of a resonant converter based on frequency conversion phase-shift control, characterized in that, The method includes: An optimized model of the circuit operating waveform under light load conditions, ignoring the resonant transient process, is established. This optimized model is used to characterize the operating waveform characteristics of the circuit under light load. Based on the optimization model, the following assumptions are set: The first condition is that the resonant current equals the excitation current at the moment the dead zone of the forearm ends. The second condition is that the dead zone of the leading arm achieves zero-voltage turn-on of the critical switching transistor, and the resonant current of the dead zone of the lagging arm is approximately equal to the excitation current. The third condition is that the dead time of the lagging arm is comparable to that of the forearm dead time, so that the dead time can be used as a single variable. Based on the optimization model, the first condition, and the third condition, a first equation relationship is established between the resonant current and the excitation current at the critical moment of the dead zone. Based on the optimization model, the second condition, and the third condition, a second equation relationship is established between voltage gain, dead time, and phase shift duty cycle. Based on the optimization model, the three assumptions, and the established equations, the functional relationship between voltage gain and phase shift duty cycle, dead time, and switching frequency is derived. Based on the aforementioned functional relationship and the zero-voltage turn-on condition of the critical switch, the optimal phase shift duty cycle and dead time that satisfy the given voltage gain requirement are determined.

2. The method according to claim 1, characterized in that, The optimization model for establishing the circuit operating waveform under light load conditions, ignoring the resonant transient process, includes: The circuit's operating stages are divided by time-domain analysis. Based on the optimization model, the operating stages are defined as the hysteresis dead zone LCC resonance stage, LC resonance stage, forearm dead zone LCC resonance stage, and LLC resonance circulating stage. An optimization model is established based on the circuit operating waveforms at each operating stage, neglecting the resonance transient process under light load conditions.

3. The method according to claim 2, characterized in that, The assumptions set based on the optimization model include: Using the characteristic information of the working waveforms at each working stage in the optimization model, assumptions are set to make the assumptions consistent with the actual working waveform trend of the circuit. Among them, the first condition corresponds to the current characteristic information at the end of the dead zone of the leading arm in the optimization model, the second condition corresponds to the zero-voltage turn-on characteristic information of the critical switch during the dead time in the optimization model, and the third condition corresponds to the correlation characteristic information between the dead time of the lagging arm and the leading arm in the optimization model.

4. The method according to claim 3, characterized in that, The establishment of the first equation relating the resonant current and the excitation current at the critical moment of the dead zone includes: At the end of the dead zone of the forearm, make the instantaneous value of the resonant current equal to the instantaneous value of the excitation current; The instantaneous value of the excitation current is determined by the current increase under the action of the phase shift duty cycle and the reverse value of the initial excitation current. The current increase is proportional to the output voltage, excitation inductance, phase shift duty cycle, and switching cycle.

5. The method according to claim 4, characterized in that, The establishment of the second equation relating voltage gain to dead time and phase shift duty cycle includes: A positive correlation was established between voltage gain and the ratio of switching frequency to resonant frequency, such that the higher the switching frequency is relative to the resonant frequency, the greater the voltage gain tends to be. Establish a positive correlation between voltage gain and phase shift duty cycle, so that voltage gain increases when phase shift duty cycle increases; A negative correlation constraint relationship is established between voltage gain and normalized dead time, such that the voltage gain decreases as the proportion of dead time to switching cycle increases.

6. The method according to claim 1, characterized in that, The derived functional relationship between voltage gain and phase shift duty cycle, dead time, and switching frequency includes: Based on the dynamic balance characteristics of resonant current and excitation current in the first equation, and combined with the correlation law between voltage gain and various parameters in the second equation, the analysis results are obtained. The analysis incorporates the current variation characteristics of each working stage in the optimization model, as well as the impact of parasitic capacitance charging and discharging on energy transfer, to obtain the influence results; By segmenting and integrating the time-domain waveform, the analysis results and the influence results are transformed into quantitative relationships, forming a functional relationship that reflects the coordinated change of voltage gain with phase shift duty cycle, dead time and switching frequency.

7. The method according to claim 1, characterized in that, The determination of the optimal phase shift duty cycle and dead time to satisfy a given voltage gain requirement based on the aforementioned functional relationship and the zero-voltage turn-on condition of the critical switch includes: The voltage gain is analyzed as a function of phase shift duty cycle and dead time, and the range of parameter values ​​that meet the given voltage gain requirements is defined. Within the range of parameter values, a critical zero-voltage turn-on condition for the switching transistor is introduced, and parameter combinations that can achieve zero-voltage turn-on of the switching transistor are selected. Determine the phase shift duty cycle and dead time from the combinations that meet the conditions to achieve optimal voltage gain stability and switching efficiency.

8. The method according to claim 1, characterized in that, The third condition also includes: When deriving the functional relationship between voltage gain and various parameters, the dead time of the leading arm is set as the basic variable, and the dead time of the lagging arm is associated with this basic variable. After the optimal value of the dead time of the leading arm is obtained through the functional relationship, according to the requirement of the dead time of the lagging arm in the third condition, a preset margin is added to the optimal value to determine the dead time of the lagging arm, so as to ensure that the lagging arm switching transistor can achieve zero-voltage turn-on.

9. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1 to 8.

10. An electronic device, characterized in that, include: One or more processors; as well as A memory associated with the one or more processors, the memory being used to store program instructions that, when read and executed by the one or more processors, perform the steps of the method according to any one of claims 1 to 8.

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