Multi-objective optimization method and system for expansion phase-shift modulation of dual-active bridge circuit

Abstract

The invention discloses a multi-objective optimization method and system for dual active bridge circuit expansion phase shift modulation, and the method comprises the steps: calculating a voltage matching ratio, and determining an external phase shift angle ratio based on a difference value between an output voltage and an output voltage reference value; according to the voltage matching ratio and the external phase shift angle ratio, obtaining an internal phase shift angle ratio of the primary side full bridge through an offline lookup table; calculating the maximum transmission power of the dual-active bridge converter, and determining a current working mode from the six preset working modes based on the size relationship between the inner phase shift angle ratio and the outer phase shift angle ratio; generating an optimal modulation strategy through a multi-objective optimization algorithm by taking the current effective value and the current peak value as optimization objectives and combining the voltage matching ratio and the periodic parameters of the current working mode; and generating a trigger signal of each switch tube of the dual-active bridge converter. Through six-mode working area division, complete differential algorithm boundary constraint and off-line-on-line collaborative optimization, the contradiction between the current stress and the soft switching range of the converter under extended phase shift modulation is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of double active bridge (DAB) circuit extended phase-shift modulation, and particularly relates to a multi-objective optimization method and system for double active bridge circuit extended phase-shift modulation. BACKGROUND

[0002] With the rapid development of distributed energy systems and the increasing demand for sustainable energy integration, in order to further realize the better establishment of an environment-friendly society, DAB type DC-DC converters have been rapidly developed and can be selected as the interface circuit inside the energy storage system. At the same time, DAB type DC-DC converters have been applied to many different industrial scenarios for integrating a large number of sustainable energy, including high penetration photovoltaic (PV) systems, multi-type sustainable energy systems and urban hydroelectric plants.

[0003] Improving the efficiency of the interface circuit is crucial for energy transmission between different renewable energy and energy storage systems. Specifically, the layout circuit design of each port is very important for distributed energy storage systems. DAB-based DC-DC converters have attracted widespread attention due to their bidirectional power transmission capability, simple modulation strategy, high power density and wide ZVS range.

[0004] There are many modulation schemes for DAB converters that have been widely applied. The most commonly used modulation method is single phase-shift (SPS) modulation, which is characterized by adjusting the phase difference between the corresponding switch tubes of the primary side full bridge and the secondary side full bridge, and the phase difference is the same. On the basis of SPS modulation, several modulations with higher degrees of freedom are proposed, including extended phase-shift (EPS) modulation, dual phase-shift (DPS) modulation and triple phase-shift (TPS) modulation. Current studies have outlined the specific conditions for achieving zero reflux power and provided analysis of the coupling relationship between existing optimization methods. However, the zero reflux power scheme is limited to only six switches achieving zero voltage switching (ZVS); this limitation stems from the fact that the duty cycle of the trigger pulse assigned to each switch is fixed at 50%, which in turn limits the optimization of the soft switching range and current stress.

[0005] Under DPS modulation, both the current performance and efficiency are worse compared with the performance and efficiency achieved under EPS and TPS modulation strategies. Under DPS modulation, the internal phase shift angles of both sides are the same, while TPS modulation can further improve the efficiency performance by increasing the number of control degrees of freedom. In addition, the analysis of ZVS performance has not been fully solved. It is challenging to achieve the optimization of circuit parameters and the expansion of ZVS range at the same time, and there are few current solutions to achieve simultaneous ZVS operation of all switching tubes. New modulation schemes have also been proposed, such as the combination of triangular modulation technology and trapezoidal modulation technology, which can reduce losses in a wide power range, but the modulation method is very complex. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a dual active bridge circuit extended phase shift modulation multi-objective optimization method and system to solve the technical problems of low overall efficiency, incomplete soft switching analysis, and existing optimization methods that cannot balance soft switching range and current stress in the prior art.

[0007] The application adopts the following technical solutions:

[0008] A dual active bridge circuit extended phase shift modulation multi-objective optimization method, comprising the following steps:

[0009] Determine the input voltage, output voltage and output voltage reference value of the dual active bridge converter;

[0010] Calculate the voltage matching ratio through the input voltage, output voltage and transformer ratio, and determine the outer phase shift angle ratio D2 based on the difference between the output voltage and the output voltage reference value;

[0011] According to the voltage matching ratio and the outer phase shift angle ratio, obtain the inner phase shift angle ratio D1 of the primary side full bridge through the offline lookup table;

[0012] Calculate the maximum transmission power of the dual active bridge converter, and determine the current working mode from the six preset working modes based on the size relationship between the inner phase shift angle ratio D1 and the outer phase shift angle ratio D2;

[0013] Take the current effective value and current peak value as the optimization target, combine the voltage matching ratio and the period parameters of the current working mode, and generate the optimal modulation strategy through the multi-objective optimization algorithm; generate the trigger signal of each switching tube of the dual active bridge converter according to the optimal modulation strategy.

[0014] Preferably, the voltage matching ratio k is:

[0015]

[0016] Where g is the voltage gain; V1 is the input voltage, V2 is the output voltage, and n is the high-frequency transformer ratio.

[0017] Preferably, the outer phase shift angle ratio D2 is specifically:

[0018] The output voltage of the secondary side full bridge is collected, and the output voltage V2 is subtracted from the output voltage reference value. According to the difference, the outer phase shift angle ratio D2 between the primary side full bridge power switch driving signal and the secondary side full bridge power switch driving signal is calculated by a proportional integral controller.

[0019] Preferably, based on the size relationship between the inner phase shift angle ratio D1 and the outer phase shift angle ratio D2, the current working mode is determined from the six preset working modes. When D1>D2, the transmission power is as follows:

[0020]

[0021] When D1<D2, the transmission power is as follows:

[0022]

[0023] Where, T hs is half of the switching period, V h1 is the output voltage of the primary side full bridge, i L is the output current of the primary side full bridge, n is the primary and secondary side ratio of the transformer, f s is the switching frequency, and L is the series inductance of the transformer in the primary side.

[0024] Preferably, the current effective value formula and the current peak value are calculated as follows:

[0025]

[0026] Where, ΔI RMS is the change of current effective value flowing through the switch when the switch is turned on, ΔD1 is the difference between the inner phase shift angle ratio of the primary side full bridge in the optimization method and the two iteration results, ΔD2 is the difference between the outer phase shift angle ratio between the primary side full bridge power switch driving signal and the secondary side full bridge power switch driving signal in the optimization method and the two iteration results, ΔI sw1 is the current instantaneous value change amount flowing through the switch when the first switch operates, ΔI sw2 is the current instantaneous value change amount flowing through the switch when the second switch operates, ΔI sw3 is the current instantaneous value change amount flowing through the switch when the third switch operates, I swn is the current instantaneous value change amount flowing through the switch when the nth switch operates, is I RMS The partial derivative of D1 is taken, is I sw1 The partial derivative of D2 is taken, and the remaining formula is the same.

[0027] Preferably, a complete differential algorithm is used to set the corresponding optimization boundary for the sub-optimization objective, by ensuring that ΔI RMS and ΔI swi The sign is negative to achieve multi-objective optimization, i = 1, 2, ..., n, the mathematical rules of the complete differential algorithm are as follows:

[0028]

[0029] Among them, ΔI RMS is the effective value change of the current flowing through the switch tube when the switch tube is turned on, ΔD1 is the difference between the two iterative results of the internal phase shift angle ratio of the primary full bridge in the optimization method, ΔD2 is the difference between the external phase shift angle ratio between the primary full bridge power switch tube drive signal and the secondary full bridge power switch tube drive signal in the optimization method, ΔI sw1 When the first switch is activated, ΔI sw2 ΔI is the instantaneous change in the current flowing through the switch tube when the second switch tube is activated. sw3 is the instantaneous change in the current flowing through the switch tube when the third switch tube is activated, I swn is the instantaneous change in the current flowing through the switch tube when the nth switch tube is activated, For I RMS Find the partial differential of D1, For I sw1 Find the partial differential of D2, and the same goes for the other equations.

[0030] Preferably, a complete differential algorithm is used to set the corresponding optimization boundary for the sub-optimization objective, by ensuring that ΔI RMS and ΔI swi Exceeds the specified threshold ΔI set , i = 1, 2, ..., n, so that the current peak is minimized, the mathematical rules of the complete differential algorithm are as follows:

[0031]

[0032] Among them, ΔI RMS is the effective value change of the current flowing through the switch tube when the switch tube is turned on, ΔD1 is the difference between the internal phase shift angle ratio of the primary full-bridge power switch tube in the optimization method disclosed in the invention, ΔD2 is the difference between the external phase shift angle ratio between the primary full-bridge power switch tube drive signal and the secondary full-bridge power switch tube drive signal in the optimization method disclosed in the invention, ΔI sw1 ΔI is the instantaneous change in the current flowing through the switch tube when the first switch tube is turned on or off. sw2 ΔI is the instantaneous change in the current flowing through the switch tube when the second switch tube is activated. sw3 is the instantaneous change in the current flowing through the switch tube when the third switch tube is activated, Iswn ΔI1 is the current instantaneous value change amount of the first switch tube when the first switch tube is in action, i.e. when the switch tube is turned on or turned off, I1 is the current instantaneous value of the first switch tube when the first switch tube is in action, i.e. when the switch tube is turned on or turned off, RMS D1 is the partial derivative of D1, I1 is the current instantaneous value of the first switch tube when the first switch tube is in action, i.e. when the switch tube is turned on or turned off, sw1 D2 is the partial derivative of D2, and the remaining formula is the same, ΔI1 set D1 is the specified threshold value.

[0033] Preferably, the direction of the inductor current is limited as follows:

[0034]

[0035] I1 is the current instantaneous value of the first switch tube when the first switch tube is in action, i.e. when the switch tube is turned on or turned off, sw1 ΔI1 is the current instantaneous value change amount of the first switch tube when the first switch tube is in action, i.e. when the switch tube is turned on or turned off, I1 sw2 ΔI2 is the current instantaneous value change amount of the second switch tube when the second switch tube is in action, I1 sw3 ΔI3 is the current instantaneous value change amount of the third switch tube when the third switch tube is in action, I1 sw4 ΔI4 is the current instantaneous value change amount of the fourth switch tube when the fourth switch tube is in action.

[0036] Preferably, ΔD1 and ΔD2 are calculated as follows:

[0037]

[0038] I1 is the current instantaneous value of the first switch tube when the first switch tube is in action, i.e. when the switch tube is turned on or turned off, D1 is the internal phase angle ratio of the primary full-bridge in the i+1th iteration of the optimization method disclosed in the application, D2 is the external phase angle ratio between the primary full-bridge power switch tube driving signal and the secondary side full-bridge power switch tube driving signal in the i+1th iteration of the optimization method disclosed in the application, D1 is the internal phase angle ratio of the primary full-bridge in the i+1th iteration of the optimization method disclosed in the application, D2 is the external phase angle ratio between the primary full-bridge power switch tube driving signal and the secondary side full-bridge power switch tube driving signal in the i+1th iteration of the optimization method disclosed in the application.

[0039] In a second aspect, the embodiments of the present application provide a multi-objective optimization system for dual active bridge circuit extended phase shift modulation, comprising:

[0040] A parameter module determines the input voltage, output voltage and output voltage reference value of the dual active bridge converter;

[0041] A first calculation module calculates the voltage matching ratio through the input voltage, output voltage and transformer ratio, and determines the external phase angle ratio D2 based on the difference between the output voltage and the output voltage reference value;

[0042] The second calculation module obtains the inner phase shift angle ratio D1 of the primary side full-bridge through an offline lookup table according to the voltage matching ratio and the outer phase shift angle ratio.

[0043] The working module calculates the maximum transmission power of the dual active bridge converter, and determines the current working mode from six preset working modes based on the size relationship between the inner phase shift angle ratio D1 and the outer phase shift angle ratio D2.

[0044] The optimization module generates an optimal modulation strategy through a multi-objective optimization algorithm with the current effective value and the current peak value as the optimization targets, in combination with the voltage matching ratio and the period parameters of the current working mode, and generates the trigger signals of the switching tubes of the dual active bridge converter according to the optimal modulation strategy.

[0045] In a third aspect, a computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the multi-objective optimization method for extended phase-shift modulation of a dual active bridge circuit when executing the computer program.

[0046] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium including a computer program, and the computer program implements the steps of the multi-objective optimization method for extended phase-shift modulation of a dual active bridge circuit when executed by a processor.

[0047] In a fifth aspect, a chip includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the multi-objective optimization method for extended phase-shift modulation of a dual active bridge circuit when executing the computer program.

[0048] In a sixth aspect, an embodiment of the present application provides an electronic device including a computer program, and the computer program implements the steps of the multi-objective optimization method for extended phase-shift modulation of a dual active bridge circuit when executed by the electronic device.

[0049] Compared with the prior art, the present application has at least the following beneficial effects:

[0050] A multi-objective optimization method for extended phase-shift modulation of a dual active bridge circuit, the input / output voltage and the transformer ratio calculate the voltage matching ratio, which provides a reference for power transmission, the outer phase shift angle D2 is dynamically generated by the output voltage error through a PI controller to realize closed-loop voltage stabilization, the inner phase shift angle D1 is pre-stored based on the voltage matching ratio and D2, which avoids solving complex equations online and reduces the DSP calculation burden, six working modes are distinguished according to the size relationship between D1 and D2 to match different transmission power requirements and avoid the deterioration of current stress in a single mode, the current effective value and the peak value are used as optimization targets, and the particle swarm algorithm and the complete differential algorithm are combined to generate an optimal strategy to realize the collaborative minimization of loss and stress.

[0051] Furthermore, the k value determines the feasible domain of the optimal phase shift angle. For example, when k>1, the phase shift angle needs to be adjusted to avoid backflow power. This provides a theoretical basis for the offline lookup table and converts the circuit parameters into the per-unit value k, facilitating a unified analysis of the transmission power boundary under different working conditions.

[0052] Furthermore, the secondary side output voltage is collected, compared with the reference value, and then output to D2 through the PI controller to suppress voltage fluctuations caused by sudden load changes. Compared with open-loop control, the closed-loop design improves system robustness and adapts to working conditions with input voltage fluctuations of ±20%. D2 is directly related to the phase difference of the primary / secondary side full-bridge drive signals to ensure controllable bidirectional power flow.

[0053] Furthermore, the six modes cover the entire range from light load to heavy load, reducing the reflux power and improving efficiency at light load.

[0054] Furthermore, the effective value of the current determines the conduction loss, and the peak current affects the stress of the switching device and the risk of saturation of the magnetic component. Based on the piecewise linear waveform of the switching cycle, the current expression for each time period is derived, providing a quantifiable optimization objective function for the PSO algorithm.

[0055] Furthermore, the forced ΔI RMS and ΔI swi The sign is negative to ensure that the current stress is strictly reduced during the iteration to avoid optimization stagnation and set the threshold ΔI set , requiring ΔI RMS and ΔI swi The solution is updated only when it exceeds the set value to prevent falling into the local optimum. Combining the optimization of the fundamental and third harmonic components, the effective value of the current is reduced by 15% to 30% compared with traditional SPS modulation.

[0056] It can be understood that the beneficial effects of the second to sixth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0057] In summary, the present invention solves the contradiction between current stress and soft switching range of the DAB converter under extended phase-shift modulation through six-mode working area division, boundary constraints of the complete differential algorithm, and offline-online collaborative optimization, providing key technical support for efficient energy conversion in new energy systems.

[0058] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 Schematic diagram of the topology of a dual active bridge converter according to an embodiment of the present invention;

[0060] Figure 2 This is a flow chart of a multi-objective optimization method according to an embodiment of the present invention;

[0061] Figure 3 Waveform diagrams of several typical working modes of the extended phase modulation of the embodiments of the present application, wherein (a) is a typical working mode 1 when 0≤D2≤D1≤1 and the voltage conversion ratio is 2<k<5, (b) is a typical working mode 2 when 0≤D2≤D1≤1 and the voltage conversion ratio is k>5, (c) is a typical working mode 5 when 0≤D2≤D1≤1, (d) is a typical working mode 3 when 0≤D1≤D2≤1, (e) is a typical working mode 4 when 0≤D1≤D2≤1 and the voltage conversion ratio is k>5, and (f) is a typical working mode 1 when 0≤D1≤D2≤1 and the voltage conversion ratio is 2<k<5;

[0062] Figure 4 A flowchart of the optimization using the particle swarm algorithm of the embodiments of the present application;

[0063] Figure 5 A control execution block diagram of the embodiments of the present application;

[0064] Figure 6 A current peak value comparison diagram of the present application and other modulation strategies under different voltage matching ratios of the embodiments of the present application, wherein the voltage matching k of (a) is 1 and the voltage matching k of (b) is 1.5;

[0065] Figure 7 A current effective value comparison diagram of the present application and other modulation strategies under different voltage matching ratios of the embodiments of the present application, wherein the voltage matching k of (a) is 1 and the voltage matching k of (b) is 1.5;

[0066] Figure 8 A schematic diagram of a computer device provided by an embodiment of the present application;

[0067] Figure 9 A block diagram of a chip according to an embodiment of the present application.

[0068] Among them, 60. Computer device; 61. Processor; 62. Memory; 63. Computer program; 600. Electronic device; 610. Processing unit; 620. Storage unit; 6201. Random access storage unit; 6202. Cache storage unit; 6203. Read-only storage unit; 6204. Program / utility; 6205. Program module; 630. Bus; 640. Display unit; 650. Input / output interface; 660. Network adapter; 700. External device. DETAILED DESCRIPTION

[0069] Clearly, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort are within the protection scope of the present application.

[0070] In the description of the present application, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0071] It should also be understood that the terms used in the present application specification are only for the purpose of describing particular embodiments and are not intended to limit the present application. As used in the present application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0072] It should be further understood that the term "and / or" used in the present application specification is intended to mean one or more of any combination of the associated listed items and all possible combinations thereof, and includes these combinations, for example, A and / or B can mean the existence of A alone, the existence of B alone, or the existence of both A and B. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0073] It should be understood that although the terms first, second, third, etc. can be used in the embodiments of the present application to describe preset ranges, etc., these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from each other. For example, the first preset range can also be referred to as the second preset range, and similarly, the second preset range can also be referred to as the first preset range without departing from the scope of the embodiments of the present application.

[0074] Depending on the context, the word "if" as used herein can be interpreted to mean "when" or "while" or "in response to determining" or "in response to detecting". Similarly, the phrase "if determined" or "if detecting (a stated condition or event)" can be interpreted to mean "when determined" or "in response to determining" or "when detecting (a stated condition or event)" or "in response to detecting (a stated condition or event)", depending on the context.

[0075] Various structural diagrams according to the disclosed embodiments of the present application are shown in the drawings. These diagrams are not drawn to scale, in which certain details are exaggerated for clarity of presentation and may be omitted. The shapes of various regions, layers shown in the drawings and their relative sizes and positional relationships are merely exemplary, and in actuality may deviate due to manufacturing tolerances or technical limitations, and regions / layers with different shapes, sizes, relative positions can be additionally designed according to actual needs by those skilled in the art.

[0076] The present application provides a multi-objective optimization method for dual active bridge circuit extended phase-shift modulation, which is based on particle swarm algorithm and complete differential algorithm to optimize peak current, effective value current and widen soft switching range. Therefore, compared with existing different modulation strategies, different types of power losses can be effectively reduced. At the same time, the effective value current and the peak current can also be effectively reduced, which means that the proposed optimization method can achieve the lowest current level. The zero voltage switching (ZVS) range can also be greatly expanded.

[0077] Referring to Figure 2 The multi-objective optimization method for dual active bridge circuit extended phase-shift modulation of the present application comprises the following steps:

[0078] S1, determining the input voltage, output voltage and output voltage reference value of the dual active bridge converter;

[0079] S2, calculating the voltage matching ratio through the input voltage, output voltage and transformer ratio;

[0080] The voltage matching ratio formula is as follows:

[0081]

[0082] Wherein, k is the voltage matching ratio; g is the voltage gain; V1 is the input voltage, V2 is the output voltage, and n is the high-frequency transformer ratio.

[0083] According to the output voltage and the output voltage reference value, the outer phase-shifting angle ratio between the primary side and the secondary side full-bridge of the dual active bridge converter is obtained, specifically as follows: the output voltage of the secondary side full-bridge is collected, the output voltage is subtracted from the output voltage reference value, and according to the difference, the outer phase-shifting angle ratio D2 between the primary side full-bridge power switch tube driving signal and the secondary side full-bridge power switch tube driving signal is calculated by a proportional-integral controller.

[0084] S3, according to the voltage matching ratio and the outer phase-shifting angle ratio reference value, the corresponding primary side full-bridge inner phase-shifting angle ratio D1 is obtained from the offline lookup table according to the corresponding primary side full-bridge duty cycle and the primary side full-bridge inner phase-shifting angle ratio.

[0085] S4, the maximum transmission power required by the dual active bridge converter under different working conditions is calculated, and six typical working modes are distinguished according to the size of the inner and outer phase shift ratio;

[0086] Please refer to Figure 3 , Figure 3 (a), 3(b) and 3(c) have the same phase shift ratio, Figure 3 (d), 3(e) and 3(f) have the same phase shift angle. The calculation method of transmission power is only related to the size of the inner and outer phase shift ratio. When D1>D2, the transmission power is as follows:

[0087]

[0088] When D1<D2, the transmission power is as follows:

[0089]

[0090] The reference transmission power P is defined as ref As follows:

[0091]

[0092] S5, the optimization target is selected as the current effective value and the current peak value, and the current effective value and the current peak value are calculated by using the voltage matching value and the period of different working modes;

[0093] Based on the particle swarm optimization (PSO) algorithm, the peak current can reach the lowest under certain transmission power, based on the complete differential algorithm, the effective value current is reduced and the soft switching range is expanded, the optimal modulation strategy is solved, and the current effective value formula and the current peak value formula are as follows, see Figure 4 , the PSO algorithm with complete differential algorithm used in the application is optimized:

[0094]

[0095] Wherein, D1 is the inner phase shift ratio of the original side full bridge; D2 is the outer phase shift angle ratio between the original side full bridge power switch tube driving signal and the auxiliary side full bridge power switch tube driving signal; i is the iteration number.

[0096] The optimization target is divided into main optimization target and sub optimization target; the purpose of the complete differential algorithm proposed is to set the corresponding optimization boundary for the sub optimization target. For example, if the optimization result of the current peak value leads to the increase of the current effective value or the reduction of the soft switching range, the designed algorithm will discard this set of optimization results. There are two different methods to design the mathematical rules of the complete differential algorithm.

[0097] The first method:

[0098] By ensuring that ΔI RMS and ΔI swi (i = 1, 2,..., n) are negative, the multi-objective optimization is achieved, which is conducive to the minimization of the peak current, and at the same time, other sub-optimization objectives can be reduced.

[0099]

[0100] The second method is as follows:

[0101] By ensuring that ΔI RMS and ΔI swi (i = 1, 2,..., n) exceed a specified threshold ΔI set , the peak current is minimized, and at the same time, additional sub-objective parameters are further refined.

[0102]

[0103] After the signs of the appropriate Δ terms expressions are determined, the reduction of the RMS current (conduction loss and copper loss) and switching loss can be achieved during the peak current optimization.

[0104] In addition, in order to reduce the direction change of the inductor current, the corresponding constraints must be carefully designed. In order to ensure that all switches work under ZVS performance, and due to the inherent symmetry of the inductor current, the direction of the inductor current is limited according to the formula described in the following formula.

[0105]

[0106] S6, the EPS modulation strategy obtained according to the novel multi-objective optimization method obtains the trigger signals of each switch tube of the dual active bridge converter in the DSP.

[0107] The present application realizes lower peak current and RMS current under the EPS modulation strategy based on the combination of the full differential algorithm in the PSO algorithm. The influence of non-ideal factors such as switching transient current value on the soft switching characteristics of the EPS modulation strategy is studied. The optimization strategy proposed can realize the lowest peak current and RMS current, and at the same time, the soft switching range is widened. Therefore, the present application can analyze the influence of non-ideal factors on the soft switching characteristics of the switch tube, and effectively optimize the current stress in the dual active bridge converter through the PSO algorithm, thereby improving the working efficiency.

[0108] In another embodiment of the present application, a multi-objective optimization system for dual active bridge circuit extended phase shift modulation is provided, which can be used to realize the above-mentioned multi-objective optimization method for dual active bridge circuit extended phase shift modulation. Specifically, the multi-objective optimization system for dual active bridge circuit extended phase shift modulation includes a parameter module, a first calculation module, a second calculation module, a working module and an optimization module.

[0109] The parameter module determines an input voltage, an output voltage and an output voltage reference value of the dual active bridge converter.

[0110] The first calculation module calculates a voltage matching ratio through the input voltage, the output voltage and a transformer ratio, and determines an outer phase shift angle ratio D2 based on a difference between the output voltage and the output voltage reference value.

[0111] The second calculation module obtains an inner phase shift angle ratio D1 of the primary side full bridge through an offline lookup table according to the voltage matching ratio and the outer phase shift angle ratio.

[0112] The working module calculates a maximum transmission power of the dual active bridge converter, and determines a current working mode from six preset working modes based on a size relationship between the inner phase shift angle ratio D1 and the outer phase shift angle ratio D2.

[0113] The optimization module generates an optimal modulation strategy through a multi-objective optimization algorithm with the current working mode cycle parameters and the voltage matching ratio as optimization targets, and generates a trigger signal of each switch tube of the dual active bridge converter according to the optimal modulation strategy.

[0114] The application provides a terminal device, which comprises a processor and a memory, the memory is used for storing a computer program, the computer program comprises program instructions, and the processor is used for executing the program instructions stored in the computer storage medium. The processor can be a central processing unit (CPU), and can also be other general-purpose processors, graphics processing units (GPUs), tensor processing units (TPUs), digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components and the like, which are the computing core and control core of the terminal, and are suitable for implementing one or more instructions, and are specifically suitable for loading and executing one or more instructions to implement a corresponding method flow or a corresponding function. The processor in the embodiments of the application can be used for the operation of the multi-objective optimization method for dual active bridge circuit extended phase shift modulation, which comprises the following steps:

[0115] The input voltage, output voltage and output voltage reference value of the dual active bridge converter are determined; the voltage matching ratio is calculated through the input voltage, output voltage and transformer ratio, and the outer phase angle ratio D2 is determined based on the difference between the output voltage and the output voltage reference value; the inner phase angle ratio D1 of the primary side full bridge is obtained through the offline lookup table according to the voltage matching ratio and the outer phase angle ratio; the maximum transmission power of the dual active bridge converter is calculated, and the current working mode is determined from six preset working modes based on the size relationship between the inner phase angle ratio D1 and the outer phase angle ratio D2; the current effective value and the current peak value are taken as the optimization target, and the optimal modulation strategy is generated through the multi-objective optimization algorithm combined with the voltage matching ratio and the period parameters of the current working mode; and the trigger signals of the switches of the dual active bridge converter are generated according to the optimal modulation strategy.

[0116] Please refer to Figure 8 , the terminal device is a computer device, the computer device 60 of the embodiment includes a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and executable on the processor 61, and the computer program 63 implements the method for estimating the concentration of radioactive iodine species in the post-accident containment when executed by the processor 61, to avoid repetition, which will not be described here. Alternatively, the computer program 63 is executed by the processor 61 to realize the functions of each model / unit in the multi-objective optimization system for extended phase shift modulation of the dual active bridge circuit, to avoid repetition, which will not be described here.

[0117] The computer device 60 can be a desktop computer, a notebook computer, a palm computer, and a cloud server, etc. The computer device 60 can include, but is not limited to, a processor 61 and a memory 62. Those skilled in the art can understand that Figure 8 The computer device 60 is only an example and does not constitute a limitation on the computer device 60, and can include more or fewer components than shown, or combine certain components, or different components, for example, the computer device can also include an input / output device, a network access device, a bus, etc.

[0118] The processor 61 can be a central processing unit (CPU), and can also be other general-purpose processors, graphics processing units (GPUs), tensor processing units (TPUs), digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0119] The memory 62 can be an internal storage unit of the computer device 60, such as a hard disk or a memory of the computer device 60. The memory 62 can also be an external storage device of the computer device 60, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the computer device 60.

[0120] Further, the memory 62 can include both an internal storage unit and an external storage device of the computer device 60. The memory 62 is used to store computer programs and other programs and data required by the computer device. The memory 62 can also be used to temporarily store data that has been output or will be output.

[0121] Please refer to Figure 9 , the terminal device is an electronic device 600, and the electronic device 600 is in the form of a general-purpose computing device. The components of the electronic device can include but are not limited to: at least one processing unit 610, at least one storage unit 620, a bus 630 connecting different platform components (including the storage unit 620 and the processing unit 610), a display unit 640, etc.

[0122] Among them, the storage unit stores program codes, and the program codes can be executed by the processing unit 610, so that the processing unit 610 executes the steps of various exemplary embodiments according to the present application described in the method part of the present specification. For example, the processing unit 610 can execute the steps as shown in Figure 2 .

[0123] The storage unit 620 may include a readable medium in the form of a volatile storage unit, such as a random access memory unit (RAM) 6201 and / or a cache memory unit 6202 , and may further include a read-only memory unit (ROM) 6203 .

[0124] The storage unit 620 may also include a program / utility 6204 having a set (at least one) of program modules 6205, such program modules 6205 including but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment.

[0125] Bus 630 may represent one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of a variety of bus architectures.

[0126] The electronic device 600 may also communicate with one or more external devices 700 (e.g., a keyboard, a pointing device, a Bluetooth device, etc.), one or more devices that enable a user to interact with the electronic device 600, and / or any device that enables the electronic device 600 to communicate with one or more other computing devices (e.g., a router, a modem). Such communication may occur via an input / output interface 650. Furthermore, the electronic device 600 may also communicate with one or more networks (e.g., a local area network, a wide area network, and / or a public network, such as the Internet) via a network adapter 660. The network adapter 660 may communicate with other modules of the electronic device 600 via a bus 630. It should be understood that, although not shown in the figures, other hardware and / or software modules may be used in conjunction with the electronic device 600, including but not limited to microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms.

[0127] Example 4

[0128] The present application further provides a storage medium, specifically a computer readable storage medium, which is a memory device in the terminal device, and is used to store programs and data. It can be understood that the computer readable storage medium herein can include the built-in storage medium in the terminal device, and of course can include the expansion storage medium supported by the terminal device, and can be any tangible medium containing or storing programs, which can be used by or in combination with an instruction execution system, device or apparatus. The computer readable storage medium provides a storage space, which stores the operating system of the terminal. Moreover, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and the instructions can be one or more computer programs (including program codes). It should be noted that more specific examples of the computer readable storage medium include an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory, an optical fiber, a portable compact disk read-only memory, an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0129] The computer readable storage medium further includes a data signal carried in baseband or propagated as a carrier wave, in which readable program codes are borne. Such a propagated data signal can take various forms, including but not limited to electro-magnetic signal, optical signal or any suitable combination of the above. The readable storage medium can also be any readable medium other than the readable storage medium, which can send, propagate or transmit programs for use by or in combination with an instruction execution system, device or apparatus. The program codes contained in the readable storage medium can be transmitted by any suitable medium, including but not limited to wireless, wired, optical cable, radio frequency, etc., or any suitable combination of the above.

[0130] The program codes for executing the operation of the present application can be written in any combination of one or more programming languages, including object-oriented programming languages such as Java, C++, etc., and conventional procedural programming languages such as "C" language or similar programming languages. The program codes can be executed entirely on the user computing device, partially on the user device, as an independent software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case involving a remote computing device, the remote computing device can be connected to the user computing device through any kind of network, including local area network or wide area network, or can be connected to an external computing device (for example, connected through the Internet by using an Internet service provider).

[0131] The one or more instructions stored in the computer readable storage medium can be loaded and executed by the processor to implement the corresponding steps of the multi-objective optimization method for dual active bridge circuit extended phase shift modulation in the above embodiments; the one or more instructions stored in the computer readable storage medium are loaded and executed by the processor to implement the following steps:

[0132] The input voltage, the output voltage and the output voltage reference value of the dual active bridge converter are determined; the voltage matching ratio is calculated through the input voltage, the output voltage and the transformer ratio, and the outer phase shift angle ratio D2 is determined based on the difference between the output voltage and the output voltage reference value; the inner phase shift angle ratio D1 of the primary side full bridge is obtained through the offline lookup table according to the voltage matching ratio and the outer phase shift angle ratio; the maximum transmission power of the dual active bridge converter is calculated, and the current working mode is determined from the six preset working modes based on the size relationship between the inner phase shift angle ratio D1 and the outer phase shift angle ratio D2; the optimal modulation strategy is generated through the multi-objective optimization algorithm with the current effective value and the current peak value as the optimization target, combined with the voltage matching ratio and the period parameters of the current working mode; the trigger signals of the switching tubes of the dual active bridge converter are generated according to the optimal modulation strategy.

[0133] The database involved in each embodiment provided by the application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a blockchain, and the like, without being limited thereto. The processor involved in each embodiment provided by the application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, and the like, without being limited thereto.

[0134] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0135] Embodiment 5

[0136] The dual active bridge converter circuit topology adopted by the present application is as shown in Figure 1 , which includes:

[0137] Four power switches S1-S4 on the primary side and four power switches Q1-Q4 on the secondary side.

[0138] D si is S i (i=1~12) anti-parallel diode.

[0139] D Qi is Q i (i=1~12) anti-parallel diode.

[0140] C1 and C2 are input filter capacitors.

[0141] C2 and C2 are output filter capacitors.

[0142] V1 and V2 represent input voltage and output voltage, respectively.

[0143] Primary side and secondary side are connected through high-frequency transformer (HFT) and inductance L.

[0144] V h1 and V h2 represent the AC equivalent output voltage of the primary side and the secondary side.

[0145] T s represents the switching period of the switch tube, T hs is half of the switching period of the switch tube.

[0146] By controlling the internal phase angle D1 between the trigger signal of the primary H-bridge switch tube S1 and the trigger signal of the switch tube S4, and the external phase angle D2 between the primary H-bridge switch tube S1 and the secondary H-bridge switch tube Q1, the current stress under the same transmission power can be reduced. Due to the symmetry of the inductance current under the proposed EPS modulation method, the analysis of power, current and soft switching characteristics will be completed in half of the switching period.

[0147] The instantaneous current stress under the conditions of D1>D2 and D1<D2 is represented as i1(t) and i2(t), respectively; in order to estimate the working condition (buck working mode or boost working mode), the concepts of voltage conversion ratio k and voltage increment g are introduced:

[0148]

[0149] Due to the symmetry of the current waveform, the division of the operating region depends on the signs of the transient current values i(t0), i(t1) and i(t2). The specific classification under the condition of D1>D2 is shown in the following table, and the detailed current expression at each switching time point is shown in the following formula:

[0150]

[0151] The specific classification under the condition of D1<D2 is shown in the following table, and the detailed current expression at each switching time point is shown in the following formula:

[0152]

[0153] Several typical working mode waveforms of the converter are shown in the appendix Figure 2 as follows.

[0154] Generally, the effective value current stress optimization is adopted to reduce the overall loss of the converter. According to the calculation results based on MATLAB, taking the condition when k > 2 as an example, the following conclusions are obtained:

[0155] 1) As Figure 3 (a) and the appendix Figure 3 (f) show, when the parameter voltage conversion ratio 2 < k < 5, only the power switches S1 and S4 are allowed to achieve the ZVS performance. This phenomenon is attributed to the narrow soft-switching range and the significant switching losses generated by optimizing the effective value current.

[0156] 2) According to the above analysis, when the parameter voltage conversion ratio 2 < k < 5, the instantaneous current stress experienced at each switching moment increases significantly, resulting in a substantial increase in switching losses and a significant reduction in efficiency.

[0157] 3) As Figure 3 (b) and Figure 3 (e) show, when k > 5, the minimum point of the effective value current stress is located at the moment of t1 or t4, which is beneficial to all power semiconductors to achieve the ZVS performance. Optimizing the ZVS range and the effective value current of all power semiconductors is considered the most effective method.

[0158] 4) At the same power level, for 2 < k < 5, implementing the minimum reflux power scheme or the minimum peak current scheme significantly expands the soft-switching range, while resulting in a relatively high effective value current stress.

[0159] As the per-unit value of the transmission power increases from 0 to 0.5, representing the transition from light load to medium load, the switching losses constitute most of the total power losses. As the per-unit value of the transmission power increases from 0.5 to 1, transitioning from medium load to heavy load scenario, the conduction losses constitute most of the overall power losses.

[0160] To improve the steady-state working efficiency performance of the dual-active-bridge converter, the detailed mathematical modeling of different types of power losses is crucial, and the proposed multi-objective optimization method is implemented accordingly to reduce the corresponding power losses, thereby improving the efficiency performance. Different types of power loss models can be divided into four different types: the conduction losses of power switches, the switching losses of power switches, the copper losses of high-frequency transformers and inductors, and the iron losses of high-frequency transformers.

[0161] The conduction losses have a great impact on the efficiency performance of the dual-active-bridge converter, denoted as Pcond whose value is closely related to the current effective value I RMS ; R ds(on) is the on-resistance of the respective power switch S i when S i is in the on-state; the on-loss P cond can be calculated by the multiplication between the effective value of the current I RMS and the on-resistance; the calculation method thereof is expressed as:

[0162]

[0163] The switching loss (P sw ) can be divided into the turn-on loss P turn-on and the turn-off loss P turn-off . The calculation methods of P turn-on and P turn-of f are described in the following two equations. Both P turn-on and P turn-off are related to the current value I sw at different switching times and the energy related to the turn-on process and the turn-off process. With the increase of the current I sw , the turn-on energy E turn-on and the turn-off energy E turn-off rise accordingly. The reduction of the switching loss is crucial for improving the overall efficiency, which is mainly due to the inherent nature of the switching process, in which the drain-source voltage across the switch S1 will not decrease to zero before the inductor current begins to increase. Therefore, by carefully arranging the transitions between switching states, P turn-on and P turn-off can be eliminated.

[0164]

[0165] where f sw represents the switching frequency, t on and t off represent the time intervals of the turn-on process and the turn-off process, respectively. The drain-to-source voltage in the on-state is represented by V ce (t), and the inductor current is represented by i L (t). In addition, E turn-on and E turn-off are mainly affected by the junction temperature T j of the respective switch and the current value I sw at a specific switching time.

[0166] The conduction loss (P trans ) in the high-frequency transformer is the sum of the copper loss P copper and the iron loss P iron . P copper can be calculated using the following formula:

[0167]

[0168] Iron loss (P iron ) is a complex phenomenon, mainly dependent on switching frequency f s and the variation of control hysteresis curve, which can be estimated by Steinmetz equation:

[0169]

[0170] Where B is the peak flux density, C m , α and β are empirical parameters:

[0171] B = V2 / (4Nf s × A core )

[0172] Where N is the turns ratio of the high-frequency transformer, A core is the cross-sectional area of the core.

[0173] A detailed mathematical modeling of different types of power losses, a comprehensive optimization strategy is proposed in the following to optimize both peak current value and RMS current value and to widen the soft-switching range. Optimization of current RMS is beneficial to reduce the conduction losses of power switches and copper losses of high-frequency transformers, while the expansion of soft-switching range helps to reduce switching losses. Switching losses are closely related to the current value I sw at the switching time, and the switching losses increase accordingly as I sw-i (i = 1, 2,..., n) increases. In addition, it is crucial to maintain the direction of inductor current throughout the optimization process, as this direction plays an important role in the overall effectiveness of the optimization strategy.

[0174] The present specification proposes a multi-objective optimization method using PSO algorithm, which specifies the peak current as the main optimization target. The developed multi-objective enhanced framework aims to enhance both peak current optimization, minimize RMS current and widen the zero-voltage switching (ZVS) operating boundary simultaneously. Through the optimization process, this study also establishes an analytical model that combines a full differential algorithm to minimize conduction losses while expanding the ZVS implementation field and enhancing soft-switching performance characteristics.

[0175] The main optimization targets of the multi-objective optimization strategy proposed by the present invention are as follows:

[0176] i peak =i peak (D1,D2,k)

[0177] The implementation of ZVS directly depends on the inductive current i LThe direction of (t). This operation requires to be included as a constraint inequality to achieve ZVS on all switching tubes, and the working area under several different EPS modulation strategies will also be considered as inequality constraints:

[0178]

[0179] The equation constraints are as follows:

[0180] P=P ref

[0181] Please refer to Figure 5 , the method flow chart of the EPS modulation strategy under the multi-objective optimization method of the application, the specific implementation process includes the following steps:

[0182] Step 1, measure the input voltage V1 and output voltage V2 of the dual active bridge converter;

[0183] Step 2, calculate the voltage conversion ratio k according to the measured input voltage V1 and output voltage V2, and obtain the output voltage V2 and the given value V 2ref After the difference, the phase angle ratio D2 of the primary H-bridge switching tube S1 trigger signal and the secondary H-bridge switching tube Q1 trigger signal is obtained through the proportional integral controller, and the drive signal of the primary full-bridge switching tube S1 and the phase shift ratio D1 of the switching tube S4 are obtained through the offline lookup table;

[0184] Step 3, determine the power to be transmitted by the current converter, and compare it with the maximum transmission power to obtain the transmission power unit P ref , according to which the current working mode operation boundary constraint condition is determined to select the working mode;

[0185] Step 4, taking the current effective value and the current peak value as the optimization target, the PSO algorithm is used for optimization and solving, wherein the equation constraint is determined by the transmission power unit, the inequality constraints are respectively the soft switching boundary constraint and the working mode operation boundary constraint, and the optimal modulation scheme (D1(opt), D2(opt)) is obtained;

[0186] Step 5, after obtaining the optimal modulation scheme (D1(opt), D2(opt)), according to the EPS modulation strategy, the trigger signals of all switching tubes S 1～4 and Q 1～4 of the dual active bridge converter are obtained.

[0187] To verify the superiority of the proposed new multi-objective optimization method based on PSO algorithm and total differential algorithm, the existing modulation schemes in the dual active bridge converter are comprehensively compared, including the proposed new multi-objective optimization method using the typical EPS modulation method, the traditional DPS and TPS modulation methods, and the evaluation under different k values and transmission power P.

[0188] The current peak value and current effective value of the traditional several modulation strategies and the EPS modulation strategy of the proposed new multi-objective optimization method based on PSO algorithm and total differential algorithm under the condition of the same transmission power are compared and analyzed in the application. As shown in the accompanying Figure 6 Figures, the proposed strategy and its optimization method exhibit the lowest current peak value under different voltage conversion ratios k. The accompanying Figure 7 Figures show that the strategy and optimization method of the application also have the lowest current effective value under different voltage conversion ratios k.

[0189] In summary, the multi-objective optimization method and system for extended phase-shift modulation of the dual active bridge circuit can effectively reduce current stress, expand the working range of soft switching, and thus significantly reduce the switching loss of the switch tube in the dual active bridge converter and improve the overall efficiency of the converter.

[0190] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is exemplified, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit, and the integrated unit can be realized in the form of hardware or software. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the application. The specific working process of the units and modules in the system can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0191] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0192] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed in the present application can be realized in electronic hardware or in combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0193] In the embodiments provided by the present application, it should be understood that the disclosed apparatus / terminal and method can be implemented in other ways. For example, the apparatus / terminal embodiments described above are merely schematic. The division of the modules or units is merely a logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed coupling or direct coupling or communication connection between the units can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or in other forms.

[0194] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. they can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0195] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0196] The integrated module / unit, if realized in the form of a software function unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on such understanding, all or part of the processes in the above-mentioned embodiment methods can also be completed by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of each method embodiment when executed by a processor. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or some intermediate forms, etc. The computer-readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the computer-readable medium can include or exclude contents according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0197] The present application is described with reference to flowcharts and / or block diagrams of methods, devices, and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device that implements the flowcharts and / or block diagrams. Figure One The flow or multiple flows and / or blocks Figure One The device that implements the functions specified in one or more flows or blocks.

[0198] These computer program instructions can also be stored in a computer-readable memory that can guide the computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including instruction devices that implement the flowcharts and / or block diagrams. Figure One The flow or multiple flows and / or blocks Figure One The device that implements the functions specified in one or more flows or blocks.

[0199] These computer program instructions can also be loaded into a computer or other programmable data processing devices, so that a series of operational steps are performed on the computer or other programmable data processing devices to generate a computer implemented process, so that the instructions executed on the computer or other programmable data processing devices provide a process for implementing the flowchart Figure One one flow or multiple flows and / or blocks Figure One Figure One one block or multiple blocks.

[0200] The above is only to illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the claims of the present application.

Claims

1. A multi-objective optimization method for dual active bridge circuit extended phase-shift modulation, characterized by, The method comprises the following steps: determining input voltage, output voltage and output voltage reference value of the dual active bridge converter; calculating voltage matching ratio through the input voltage, the output voltage and transformer ratio, and determining the external phase angle ratio D2 based on the difference between the output voltage and the output voltage reference value; obtaining the internal phase angle ratio D1 of the primary full-bridge through an offline lookup table according to the voltage matching ratio and the external phase angle ratio; calculating the maximum transmission power of the dual active bridge converter, and determining the current working mode from six preset working modes based on the size relationship between the internal phase angle ratio D1 and the external phase angle ratio D2; generating the trigger signal of each switch tube of the dual active bridge converter according to the optimal modulation strategy generated by the multi-objective optimization algorithm with the current effective value and the current peak value as the optimization targets, in combination with the voltage matching ratio and the period parameters of the current working mode.

2. The multi-objective optimization method for dual active bridge circuit extended phase-shift modulation according to claim 1, wherein The voltage matching ratio k is: wherein g is the voltage gain; V1 is the input voltage, V2 is the output voltage, and n is the high-frequency transformer ratio.

3. The multi-objective optimization method for dual active bridge circuit extended phase-shift modulation according to claim 1, wherein The external phase angle ratio D2 is specifically: The output voltage of the secondary full-bridge is collected, and the output voltage V2 is subtracted from the output voltage reference value, and the external phase angle ratio D2 between the primary full-bridge power switch tube driving signal and the secondary full-bridge power switch tube driving signal is calculated through a proportional-integral controller according to the difference.

4. The multi-objective optimization method for dual active bridge circuit extended phase-shift modulation according to claim 1, wherein Based on the size relationship between the internal phase angle ratio D1 and the external phase angle ratio D2, the current working mode is determined from the six preset working modes. When D1>D2, the transmission power is as follows: When D1<D2, the transmission power is as follows: Where T hs is half of the switching period, V h1 is the primary full-bridge output voltage, i L is the primary full-bridge output current, n is the transformer primary-secondary ratio, f s is the switching frequency, and L is the series inductance of the transformer in the primary side.

5. The multi-objective optimization method for dual active bridge circuit extended phase-shift modulation according to claim 1, wherein The current effective value formula and the current peak value are calculated as follows: wherein, ΔI RMS is the current effective value change amount flowing through the switch tube when the switch tube is turned on, ΔD1 is the difference between the two iteration results of the inner phase angle ratio of the primary full-bridge in the optimization method, ΔD2 is the difference between the two iteration results of the outer phase angle ratio between the primary full-bridge power switch tube driving signal and the secondary side full-bridge power switch tube driving signal in the optimization method, ΔI sw1 is the current instantaneous value change amount flowing through the switch tube when the first switch tube operates, ΔI sw2 is the current instantaneous value change amount flowing through the switch tube when the second switch tube operates, ΔI sw3 is the current instantaneous value change amount flowing through the switch tube when the third switch tube operates, I swn is the current instantaneous value change amount flowing through the switch tube when the nth switch tube operates, is I RMS the partial derivative of D1 is taken, is I sw1 the partial derivative of D2 is taken.

6. The multi-objective optimization method for dual active bridge circuit extended phase-shift modulation according to claim 5, wherein The complete differential algorithm is used to set the corresponding optimization boundary for the sub-optimization target, and the multi-objective optimization is realized by ensuring that the signs of ΔI RMS and ΔI swi are negative, i = 1, 2, …, n, and the mathematical rules of the complete differential algorithm are as follows: wherein, ΔI RMS is the current effective value change amount flowing through the switch tube when the switch tube is turned on, ΔD1 is the difference between the two iteration results of the inner phase angle ratio of the primary full-bridge in the optimization method, ΔD2 is the difference between the two iteration results of the outer phase angle ratio between the primary full-bridge power switch tube driving signal and the secondary side full-bridge power switch tube driving signal in the optimization method, ΔI sw1 is the current effective value change amount flowing through the switch tube when the first switch tube operates, sw2 is the current instantaneous value change amount flowing through the switch tube when the second switch tube operates, ΔI sw3 is the current instantaneous value change amount flowing through the switch tube when the third switch tube operates, I swn is the current instantaneous value change amount flowing through the switch tube when the nth switch tube operates, is I RMS the partial derivative of D1 is taken, is I sw1 the partial derivative of D2 is taken.

7. The multi-objective optimization method for dual active bridge circuit extended phase-shift modulation according to claim 5, wherein The complete differential algorithm sets the corresponding optimization boundary for the sub-optimization target, and ensures that ΔI RMS and ΔI swi exceed the specified threshold ΔI set , i = 1, 2, …, n, so as to minimize the current peak value. The mathematical rule of the complete differential algorithm is as follows: wherein, ΔI RMS is the current effective value change amount flowing through the switch tube when the switch tube is turned on, ΔD1 is the difference between the two iteration results of the inner phase angle ratio of the primary full-bridge in the optimization method, ΔD2 is the difference between the two iteration results of the outer phase angle ratio between the primary full-bridge power switch tube driving signal and the secondary side full-bridge power switch tube driving signal in the optimization method, ΔI sw1 is the current effective value change amount flowing through the switch tube when the first switch tube operates, sw2 is the current instantaneous value change amount flowing through the switch tube when the second switch tube operates, ΔI sw3 is the current instantaneous value change amount flowing through the switch tube when the third switch tube operates, I swn is the current instantaneous value change amount flowing through the switch tube when the nth switch tube operates, is I RMS the partial derivative of D1 is taken, is I sw1 the partial derivative of D2 is taken, ΔI set is a specified threshold value.

8. The multi-objective optimization method for dual active bridge circuit extended phase-shift modulation according to claim 5, wherein, The direction of the inductor current is limited as follows: wherein, I sw1 is the current transient value flowing through the switch tube at the time of the first switch tube operation, i.e. at the time of switching on or switching off, I sw2 is the change in the current transient value flowing through the switch tube at the time of the second switch tube operation, I sw3 is the change in the current transient value flowing through the switch tube at the time of the third switch tube operation, I sw4 is the change in the current transient value flowing through the switch tube at the time of the fourth switch tube operation.

9. The multi-objective optimization method for dual active bridge circuit extended phase-shift modulation according to claim 5, wherein, ΔD1 and ΔD2 are calculated as follows: wherein, is the result of the i+1th iteration of the optimization method disclosed in the invention for the inner phase shift angle ratio of the primary full bridge, is the result of the i+1th iteration of the optimization method disclosed in the invention for the outer phase shift angle ratio between the primary full bridge power switch drive signal and the secondary half bridge power switch drive signal, is the result of the ith iteration of the optimization method disclosed in the invention for the inner phase shift angle ratio of the primary full bridge, is the result of the ith iteration of the optimization method disclosed in the invention for the outer phase shift angle ratio between the primary full bridge power switch drive signal and the secondary half bridge power switch drive signal.

10. A multi-objective optimization system for dual active bridge circuit extended phase-shift modulation, characterized by, It comprises: a parameter module for determining the input voltage, the output voltage and the output voltage reference value of the dual active bridge converter; a first calculation module for calculating the voltage matching ratio through the input voltage, the output voltage and the transformer ratio, and determining the external phase angle ratio D2 based on the difference between the output voltage and the output voltage reference value; a second calculation module for obtaining the internal phase angle ratio D1 of the primary full-bridge through an offline lookup table according to the voltage matching ratio and the external phase angle ratio; a working module for calculating the maximum transmission power of the dual active bridge converter, and determining the current working mode from six preset working modes based on the size relationship between the internal phase angle ratio D1 and the external phase angle ratio D2; an optimization module for generating the trigger signal of each switch tube of the dual active bridge converter according to the optimal modulation strategy generated by the multi-objective optimization algorithm with the current effective value and the current peak value as the optimization targets, in combination with the voltage matching ratio and the period parameters of the current working mode.

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